Add support for RxJava 3

Closes gh-24170

build.gradle

@@ -58,6 +58,7 @@ configure(allprojects) { project ->
 			dependency "io.reactivex:rxjava:1.3.8"
 			dependency "io.reactivex:rxjava-reactive-streams:1.2.1"
 			dependency "io.reactivex.rxjava2:rxjava:2.2.19"
+			dependency "io.reactivex.rxjava3:rxjava:3.0.3"
 			dependency "io.projectreactor.tools:blockhound:1.0.2.RELEASE"
 
 			dependency "com.caucho:hessian:4.0.62"

spring-core/spring-core.gradle

@@ -52,6 +52,7 @@ dependencies {
 	optional("io.reactivex:rxjava")
 	optional("io.reactivex:rxjava-reactive-streams")
 	optional("io.reactivex.rxjava2:rxjava")
+	optional("io.reactivex.rxjava3:rxjava")
 	optional("io.netty:netty-buffer")
 	testCompile("io.projectreactor:reactor-test")
 	testCompile("javax.annotation:javax.annotation-api")

spring-core/src/main/java/org/springframework/core/ReactiveAdapterRegistry.java

@@ -24,8 +24,6 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 import java.util.function.Function;
 
-import io.reactivex.BackpressureStrategy;
-import io.reactivex.Flowable;
 import kotlinx.coroutines.CompletableDeferredKt;
 import kotlinx.coroutines.Deferred;
 import org.reactivestreams.Publisher;
@@ -46,8 +44,9 @@ import org.springframework.util.ReflectionUtils;
  * {@code Observable}, and others.
  *
  * <p>By default, depending on classpath availability, adapters are registered
- * for Reactor, RxJava 1, RxJava 2 types, {@link CompletableFuture}, Java 9+
- * {@code Flow.Publisher} and Kotlin Coroutines {@code Deferred} and {@code Flow}.
+ * for Reactor, RxJava 2/3, or RxJava 1 (+ RxJava Reactive Streams bridge),
+ * {@link CompletableFuture}, Java 9+ {@code Flow.Publisher}, and Kotlin
+ * Coroutines' {@code Deferred} and {@code Flow}.
  *
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
@@ -89,6 +88,11 @@ public class ReactiveAdapterRegistry {
 			new RxJava2Registrar().registerAdapters(this);
 		}
 
+		// RxJava3
+		if (ClassUtils.isPresent("io.reactivex.rxjava3.core.Flowable", classLoader)) {
+			new RxJava3Registrar().registerAdapters(this);
+		}
+
 		// Java 9+ Flow.Publisher
 		if (ClassUtils.isPresent("java.util.concurrent.Flow.Publisher", classLoader)) {
 			new ReactorJdkFlowAdapterRegistrar().registerAdapter(this);
@@ -104,9 +108,7 @@ public class ReactiveAdapterRegistry {
 
 
 	/**
-	 * Whether the registry has any adapters which would be the case if any of
-	 * Reactor, RxJava 2, or RxJava 1 (+ RxJava Reactive Streams bridge) are
-	 * present on the classpath.
+	 * Whether the registry has any adapters.
 	 */
 	public boolean hasAdapters() {
 		return !this.adapters.isEmpty();
@@ -254,31 +256,78 @@ public class ReactiveAdapterRegistry {
 			registry.registerReactiveType(
 					ReactiveTypeDescriptor.multiValue(io.reactivex.Flowable.class, io.reactivex.Flowable::empty),
 					source -> (io.reactivex.Flowable<?>) source,
-					Flowable::fromPublisher
+					io.reactivex.Flowable::fromPublisher
 			);
 			registry.registerReactiveType(
 					ReactiveTypeDescriptor.multiValue(io.reactivex.Observable.class, io.reactivex.Observable::empty),
-					source -> ((io.reactivex.Observable<?>) source).toFlowable(BackpressureStrategy.BUFFER),
-					source -> io.reactivex.Flowable.fromPublisher(source).toObservable()
+					source -> ((io.reactivex.Observable<?>) source).toFlowable(io.reactivex.BackpressureStrategy.BUFFER),
+					source -> io.reactivex.Flowable.fromPublisher(source)
+							.toObservable()
 			);
 			registry.registerReactiveType(
 					ReactiveTypeDescriptor.singleRequiredValue(io.reactivex.Single.class),
 					source -> ((io.reactivex.Single<?>) source).toFlowable(),
-					source -> io.reactivex.Flowable.fromPublisher(source).toObservable().singleElement().toSingle()
+					source -> io.reactivex.Flowable.fromPublisher(source)
+							.toObservable().singleElement().toSingle()
 			);
 			registry.registerReactiveType(
 					ReactiveTypeDescriptor.singleOptionalValue(io.reactivex.Maybe.class, io.reactivex.Maybe::empty),
 					source -> ((io.reactivex.Maybe<?>) source).toFlowable(),
-					source -> io.reactivex.Flowable.fromPublisher(source).toObservable().singleElement()
+					source -> io.reactivex.Flowable.fromPublisher(source)
+							.toObservable().singleElement()
 			);
 			registry.registerReactiveType(
 					ReactiveTypeDescriptor.noValue(io.reactivex.Completable.class, io.reactivex.Completable::complete),
 					source -> ((io.reactivex.Completable) source).toFlowable(),
-					source -> io.reactivex.Flowable.fromPublisher(source).toObservable().ignoreElements()
+					source -> io.reactivex.Flowable.fromPublisher(source)
+							.toObservable().ignoreElements()
 			);
 		}
 	}
 
+	private static class RxJava3Registrar {
+
+		void registerAdapters(ReactiveAdapterRegistry registry) {
+			registry.registerReactiveType(
+					ReactiveTypeDescriptor.multiValue(
+							io.reactivex.rxjava3.core.Flowable.class,
+							io.reactivex.rxjava3.core.Flowable::empty),
+					source -> (io.reactivex.rxjava3.core.Flowable<?>) source,
+					io.reactivex.rxjava3.core.Flowable::fromPublisher
+			);
+			registry.registerReactiveType(
+					ReactiveTypeDescriptor.multiValue(
+							io.reactivex.rxjava3.core.Observable.class,
+							io.reactivex.rxjava3.core.Observable::empty),
+					source -> ((io.reactivex.rxjava3.core.Observable<?>) source).toFlowable(
+							io.reactivex.rxjava3.core.BackpressureStrategy.BUFFER),
+					source -> io.reactivex.rxjava3.core.Flowable.fromPublisher(source)
+							.toObservable()
+			);
+			registry.registerReactiveType(
+					ReactiveTypeDescriptor.singleRequiredValue(io.reactivex.rxjava3.core.Single.class),
+					source -> ((io.reactivex.rxjava3.core.Single<?>) source).toFlowable(),
+					source -> io.reactivex.rxjava3.core.Flowable.fromPublisher(source)
+							.toObservable().singleElement().toSingle()
+			);
+			registry.registerReactiveType(
+					ReactiveTypeDescriptor.singleOptionalValue(
+							io.reactivex.rxjava3.core.Maybe.class,
+							io.reactivex.rxjava3.core.Maybe::empty),
+					source -> ((io.reactivex.rxjava3.core.Maybe<?>) source).toFlowable(),
+					source -> io.reactivex.rxjava3.core.Flowable.fromPublisher(source)
+							.toObservable().singleElement()
+			);
+			registry.registerReactiveType(
+					ReactiveTypeDescriptor.noValue(
+							io.reactivex.rxjava3.core.Completable.class,
+							io.reactivex.rxjava3.core.Completable::complete),
+					source -> ((io.reactivex.rxjava3.core.Completable) source).toFlowable(),
+					source -> io.reactivex.rxjava3.core.Flowable.fromPublisher(source)
+							.toObservable().ignoreElements()
+			);
+		}
+	}
 
 	private static class ReactorJdkFlowAdapterRegistrar {
 

spring-core/src/test/java/org/springframework/core/ConventionsTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,8 +23,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
-import io.reactivex.Observable;
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;

spring-core/src/test/java/org/springframework/core/ReactiveAdapterRegistryTests.java

@@ -21,17 +21,13 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 
-import io.reactivex.Flowable;
-import io.reactivex.Maybe;
 import kotlinx.coroutines.Deferred;
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.FluxProcessor;
 import reactor.core.publisher.Mono;
-import rx.Completable;
-import rx.Observable;
-import rx.Single;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -45,35 +41,6 @@ class ReactiveAdapterRegistryTests {
 	private final ReactiveAdapterRegistry registry = ReactiveAdapterRegistry.getSharedInstance();
 
 
-	@Test
-	void defaultAdapterRegistrations() {
-
-		// Reactor
-		assertThat(getAdapter(Mono.class)).isNotNull();
-		assertThat(getAdapter(Flux.class)).isNotNull();
-
-		// Publisher
-		assertThat(getAdapter(Publisher.class)).isNotNull();
-
-		// Completable
-		assertThat(getAdapter(CompletableFuture.class)).isNotNull();
-
-		// RxJava 1
-		assertThat(getAdapter(Observable.class)).isNotNull();
-		assertThat(getAdapter(Single.class)).isNotNull();
-		assertThat(getAdapter(Completable.class)).isNotNull();
-
-		// RxJava 2
-		assertThat(getAdapter(Flowable.class)).isNotNull();
-		assertThat(getAdapter(io.reactivex.Observable.class)).isNotNull();
-		assertThat(getAdapter(io.reactivex.Single.class)).isNotNull();
-		assertThat(getAdapter(Maybe.class)).isNotNull();
-		assertThat(getAdapter(io.reactivex.Completable.class)).isNotNull();
-
-		// Coroutines
-		assertThat(getAdapter(Deferred.class)).isNotNull();
-	}
-
 	@Test
 	void getAdapterForReactiveSubType() {
 
@@ -93,192 +60,301 @@ class ReactiveAdapterRegistryTests {
 		assertThat(adapter3).isNotSameAs(adapter1);
 	}
 
-	@Test
-	void publisherToFlux() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Publisher<Integer> source = Flowable.fromIterable(sequence);
-		Object target = getAdapter(Flux.class).fromPublisher(source);
-		boolean condition = target instanceof Flux;
-		assertThat(condition).isTrue();
-		assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+	@Nested
+	class Reactor {
+
+		@Test
+		void defaultAdapterRegistrations() {
+
+			// Reactor
+			assertThat(getAdapter(Mono.class)).isNotNull();
+			assertThat(getAdapter(Flux.class)).isNotNull();
+
+			// Publisher
+			assertThat(getAdapter(Publisher.class)).isNotNull();
+
+			// Completable
+			assertThat(getAdapter(CompletableFuture.class)).isNotNull();
+		}
+
+		@Test
+		void toFlux() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Publisher<Integer> source = io.reactivex.rxjava3.core.Flowable.fromIterable(sequence);
+			Object target = getAdapter(Flux.class).fromPublisher(source);
+			assertThat(target instanceof Flux).isTrue();
+			assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+		}
+
+		@Test
+		void toMono() {
+			Publisher<Integer> source = io.reactivex.rxjava3.core.Flowable.fromArray(1, 2, 3);
+			Object target = getAdapter(Mono.class).fromPublisher(source);
+			assertThat(target instanceof Mono).isTrue();
+			assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void toCompletableFuture() throws Exception {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1, 2, 3});
+			Object target = getAdapter(CompletableFuture.class).fromPublisher(source);
+			assertThat(target instanceof CompletableFuture).isTrue();
+			assertThat(((CompletableFuture<Integer>) target).get()).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void fromCompletableFuture() {
+			CompletableFuture<Integer> future = new CompletableFuture<>();
+			future.complete(1);
+			Object target = getAdapter(CompletableFuture.class).toPublisher(future);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
+		}
 	}
 
-	// TODO: publisherToMono/CompletableFuture vs Single (ISE on multiple elements)?
-
-	@Test
-	void publisherToMono() {
-		Publisher<Integer> source = Flowable.fromArray(1, 2, 3);
-		Object target = getAdapter(Mono.class).fromPublisher(source);
-		boolean condition = target instanceof Mono;
-		assertThat(condition).isTrue();
-		assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
+	@Nested
+	class RxJava1 {
+
+		@Test
+		void defaultAdapterRegistrations() {
+			assertThat(getAdapter(rx.Observable.class)).isNotNull();
+			assertThat(getAdapter(rx.Single.class)).isNotNull();
+			assertThat(getAdapter(rx.Completable.class)).isNotNull();
+		}
+
+		@Test
+		void toObservable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Publisher<Integer> source = Flux.fromIterable(sequence);
+			Object target = getAdapter(rx.Observable.class).fromPublisher(source);
+			assertThat(target instanceof rx.Observable).isTrue();
+			assertThat(((rx.Observable<?>) target).toList().toBlocking().first()).isEqualTo(sequence);
+		}
+
+		@Test
+		void toSingle() {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1});
+			Object target = getAdapter(rx.Single.class).fromPublisher(source);
+			assertThat(target instanceof rx.Single).isTrue();
+			assertThat(((rx.Single<Integer>) target).toBlocking().value()).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void toCompletable() {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1, 2, 3});
+			Object target = getAdapter(rx.Completable.class).fromPublisher(source);
+			assertThat(target instanceof rx.Completable).isTrue();
+			assertThat(((rx.Completable) target).get()).isNull();
+		}
+
+		@Test
+		void fromObservable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Object source = rx.Observable.from(sequence);
+			Object target = getAdapter(rx.Observable.class).toPublisher(source);
+			assertThat(target instanceof Flux).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+		}
+
+		@Test
+		void fromSingle() {
+			Object source = rx.Single.just(1);
+			Object target = getAdapter(rx.Single.class).toPublisher(source);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void fromCompletable() {
+			Object source = rx.Completable.complete();
+			Object target = getAdapter(rx.Completable.class).toPublisher(source);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			((Mono<Void>) target).block(Duration.ofMillis(1000));
+		}
 	}
 
-	@Test
-	void publisherToCompletableFuture() throws Exception {
-		Publisher<Integer> source = Flowable.fromArray(1, 2, 3);
-		Object target = getAdapter(CompletableFuture.class).fromPublisher(source);
-		boolean condition = target instanceof CompletableFuture;
-		assertThat(condition).isTrue();
-		assertThat(((CompletableFuture<Integer>) target).get()).isEqualTo(Integer.valueOf(1));
+	@Nested
+	class RxJava2 {
+
+		@Test
+		void defaultAdapterRegistrations() {
+
+			// RxJava 2
+			assertThat(getAdapter(io.reactivex.Flowable.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.Observable.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.Single.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.Maybe.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.Completable.class)).isNotNull();
+		}
+
+		@Test
+		void toFlowable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Publisher<Integer> source = Flux.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.Flowable.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.Flowable).isTrue();
+			assertThat(((io.reactivex.Flowable<?>) target).toList().blockingGet()).isEqualTo(sequence);
+		}
+
+		@Test
+		void toObservable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Publisher<Integer> source = Flux.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.Observable.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.Observable).isTrue();
+			assertThat(((io.reactivex.Observable<?>) target).toList().blockingGet()).isEqualTo(sequence);
+		}
+
+		@Test
+		void toSingle() {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1});
+			Object target = getAdapter(io.reactivex.Single.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.Single).isTrue();
+			assertThat(((io.reactivex.Single<Integer>) target).blockingGet()).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void toCompletable() {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1, 2, 3});
+			Object target = getAdapter(io.reactivex.Completable.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.Completable).isTrue();
+			((io.reactivex.Completable) target).blockingAwait();
+		}
+
+		@Test
+		void fromFlowable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Object source = io.reactivex.Flowable.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.Flowable.class).toPublisher(source);
+			assertThat(target instanceof Flux).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+		}
+
+		@Test
+		void fromObservable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Object source = io.reactivex.Observable.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.Observable.class).toPublisher(source);
+			assertThat(target instanceof Flux).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+		}
+
+		@Test
+		void fromSingle() {
+			Object source = io.reactivex.Single.just(1);
+			Object target = getAdapter(io.reactivex.Single.class).toPublisher(source);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void fromCompletable() {
+			Object source = io.reactivex.Completable.complete();
+			Object target = getAdapter(io.reactivex.Completable.class).toPublisher(source);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			((Mono<Void>) target).block(Duration.ofMillis(1000));
+		}
 	}
 
-	@Test
-	void publisherToRxObservable() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Publisher<Integer> source = Flowable.fromIterable(sequence);
-		Object target = getAdapter(rx.Observable.class).fromPublisher(source);
-		boolean condition = target instanceof Observable;
-		assertThat(condition).isTrue();
-		assertThat(((Observable<?>) target).toList().toBlocking().first()).isEqualTo(sequence);
-	}
-
-	@Test
-	void publisherToRxSingle() {
-		Publisher<Integer> source = Flowable.fromArray(1);
-		Object target = getAdapter(rx.Single.class).fromPublisher(source);
-		boolean condition = target instanceof Single;
-		assertThat(condition).isTrue();
-		assertThat(((Single<Integer>) target).toBlocking().value()).isEqualTo(Integer.valueOf(1));
-	}
-
-	@Test
-	void publisherToRxCompletable() {
-		Publisher<Integer> source = Flowable.fromArray(1, 2, 3);
-		Object target = getAdapter(rx.Completable.class).fromPublisher(source);
-		boolean condition = target instanceof Completable;
-		assertThat(condition).isTrue();
-		assertThat(((Completable) target).get()).isNull();
-	}
-
-	@Test
-	void publisherToReactivexFlowable() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Publisher<Integer> source = Flux.fromIterable(sequence);
-		Object target = getAdapter(io.reactivex.Flowable.class).fromPublisher(source);
-		boolean condition = target instanceof Flowable;
-		assertThat(condition).isTrue();
-		assertThat(((Flowable<?>) target).toList().blockingGet()).isEqualTo(sequence);
-	}
-
-	@Test
-	void publisherToReactivexObservable() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Publisher<Integer> source = Flowable.fromIterable(sequence);
-		Object target = getAdapter(io.reactivex.Observable.class).fromPublisher(source);
-		boolean condition = target instanceof io.reactivex.Observable;
-		assertThat(condition).isTrue();
-		assertThat(((io.reactivex.Observable<?>) target).toList().blockingGet()).isEqualTo(sequence);
-	}
-
-	@Test
-	void publisherToReactivexSingle() {
-		Publisher<Integer> source = Flowable.fromArray(1);
-		Object target = getAdapter(io.reactivex.Single.class).fromPublisher(source);
-		boolean condition = target instanceof io.reactivex.Single;
-		assertThat(condition).isTrue();
-		assertThat(((io.reactivex.Single<Integer>) target).blockingGet()).isEqualTo(Integer.valueOf(1));
+	@Nested
+	class RxJava3 {
+
+		@Test
+		void defaultAdapterRegistrations() {
+
+			// RxJava 3
+			assertThat(getAdapter(io.reactivex.rxjava3.core.Flowable.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.rxjava3.core.Observable.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.rxjava3.core.Single.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.rxjava3.core.Maybe.class)).isNotNull();
+			assertThat(getAdapter(io.reactivex.rxjava3.core.Completable.class)).isNotNull();
+		}
+
+		@Test
+		void toFlowable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Publisher<Integer> source = Flux.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.rxjava3.core.Flowable.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.rxjava3.core.Flowable).isTrue();
+			assertThat(((io.reactivex.rxjava3.core.Flowable<?>) target).toList().blockingGet()).isEqualTo(sequence);
+		}
+
+		@Test
+		void toObservable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Publisher<Integer> source = Flux.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.rxjava3.core.Observable.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.rxjava3.core.Observable).isTrue();
+			assertThat(((io.reactivex.rxjava3.core.Observable<?>) target).toList().blockingGet()).isEqualTo(sequence);
+		}
+
+		@Test
+		void toSingle() {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1});
+			Object target = getAdapter(io.reactivex.rxjava3.core.Single.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.rxjava3.core.Single).isTrue();
+			assertThat(((io.reactivex.rxjava3.core.Single<Integer>) target).blockingGet()).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void toCompletable() {
+			Publisher<Integer> source = Flux.fromArray(new Integer[] {1, 2, 3});
+			Object target = getAdapter(io.reactivex.rxjava3.core.Completable.class).fromPublisher(source);
+			assertThat(target instanceof io.reactivex.rxjava3.core.Completable).isTrue();
+			((io.reactivex.rxjava3.core.Completable) target).blockingAwait();
+		}
+
+		@Test
+		void fromFlowable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Object source = io.reactivex.rxjava3.core.Flowable.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.rxjava3.core.Flowable.class).toPublisher(source);
+			assertThat(target instanceof Flux).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+		}
+
+		@Test
+		void fromObservable() {
+			List<Integer> sequence = Arrays.asList(1, 2, 3);
+			Object source = io.reactivex.rxjava3.core.Observable.fromIterable(sequence);
+			Object target = getAdapter(io.reactivex.rxjava3.core.Observable.class).toPublisher(source);
+			assertThat(target instanceof Flux).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
+		}
+
+		@Test
+		void fromSingle() {
+			Object source = io.reactivex.rxjava3.core.Single.just(1);
+			Object target = getAdapter(io.reactivex.rxjava3.core.Single.class).toPublisher(source);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
+		}
+
+		@Test
+		void fromCompletable() {
+			Object source = io.reactivex.rxjava3.core.Completable.complete();
+			Object target = getAdapter(io.reactivex.rxjava3.core.Completable.class).toPublisher(source);
+			assertThat(target instanceof Mono).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
+			((Mono<Void>) target).block(Duration.ofMillis(1000));
+		}
 	}
 
-	@Test
-	void publisherToReactivexCompletable() {
-		Publisher<Integer> source = Flowable.fromArray(1, 2, 3);
-		Object target = getAdapter(io.reactivex.Completable.class).fromPublisher(source);
-		boolean condition = target instanceof io.reactivex.Completable;
-		assertThat(condition).isTrue();
-		((io.reactivex.Completable) target).blockingAwait();
-	}
-
-	@Test
-	void rxObservableToPublisher() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Object source = rx.Observable.from(sequence);
-		Object target = getAdapter(rx.Observable.class).toPublisher(source);
-		boolean condition = target instanceof Flux;
-		assertThat(condition).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
-		assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
-	}
-
-	@Test
-	void rxSingleToPublisher() {
-		Object source = rx.Single.just(1);
-		Object target = getAdapter(rx.Single.class).toPublisher(source);
-		boolean condition = target instanceof Mono;
-		assertThat(condition).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
-		assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
-	}
-
-	@Test
-	void rxCompletableToPublisher() {
-		Object source = rx.Completable.complete();
-		Object target = getAdapter(rx.Completable.class).toPublisher(source);
-		boolean condition = target instanceof Mono;
-		assertThat(condition).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
-		((Mono<Void>) target).block(Duration.ofMillis(1000));
-	}
-
-	@Test
-	void reactivexFlowableToPublisher() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Object source = io.reactivex.Flowable.fromIterable(sequence);
-		Object target = getAdapter(io.reactivex.Flowable.class).toPublisher(source);
-		boolean condition = target instanceof Flux;
-		assertThat(condition).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
-		assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
-	}
-
-	@Test
-	void reactivexObservableToPublisher() {
-		List<Integer> sequence = Arrays.asList(1, 2, 3);
-		Object source = io.reactivex.Observable.fromIterable(sequence);
-		Object target = getAdapter(io.reactivex.Observable.class).toPublisher(source);
-		boolean condition = target instanceof Flux;
-		assertThat(condition).as("Expected Flux Publisher: " + target.getClass().getName()).isTrue();
-		assertThat(((Flux<Integer>) target).collectList().block(Duration.ofMillis(1000))).isEqualTo(sequence);
-	}
-
-	@Test
-	void reactivexSingleToPublisher() {
-		Object source = io.reactivex.Single.just(1);
-		Object target = getAdapter(io.reactivex.Single.class).toPublisher(source);
-		boolean condition = target instanceof Mono;
-		assertThat(condition).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
-		assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
-	}
-
-	@Test
-	void reactivexCompletableToPublisher() {
-		Object source = io.reactivex.Completable.complete();
-		Object target = getAdapter(io.reactivex.Completable.class).toPublisher(source);
-		boolean condition = target instanceof Mono;
-		assertThat(condition).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
-		((Mono<Void>) target).block(Duration.ofMillis(1000));
-	}
-
-	@Test
-	void completableFutureToPublisher() {
-		CompletableFuture<Integer> future = new CompletableFuture<>();
-		future.complete(1);
-		Object target = getAdapter(CompletableFuture.class).toPublisher(future);
-		boolean condition = target instanceof Mono;
-		assertThat(condition).as("Expected Mono Publisher: " + target.getClass().getName()).isTrue();
-		assertThat(((Mono<Integer>) target).block(Duration.ofMillis(1000))).isEqualTo(Integer.valueOf(1));
-	}
-
-	@Test
-	void deferred() {
-		assertThat(getAdapter(CompletableFuture.class).getDescriptor().isDeferred()).isEqualTo(false);
+	@Nested
+	class Kotlin {
 
-		assertThat(getAdapter(Mono.class).getDescriptor().isDeferred()).isEqualTo(true);
-		assertThat(getAdapter(Flux.class).getDescriptor().isDeferred()).isEqualTo(true);
+		@Test
+		void defaultAdapterRegistrations() {
 
-		assertThat(getAdapter(io.reactivex.Completable.class).getDescriptor().isDeferred()).isEqualTo(true);
-		assertThat(getAdapter(io.reactivex.Single.class).getDescriptor().isDeferred()).isEqualTo(true);
-		assertThat(getAdapter(io.reactivex.Flowable.class).getDescriptor().isDeferred()).isEqualTo(true);
-		assertThat(getAdapter(io.reactivex.Observable.class).getDescriptor().isDeferred()).isEqualTo(true);
+			// Coroutines
+			assertThat(getAdapter(Deferred.class)).isNotNull();
+		}
 
-		assertThat(getAdapter(Deferred.class).getDescriptor().isDeferred()).isEqualTo(true);
-		assertThat(getAdapter(kotlinx.coroutines.flow.Flow.class).getDescriptor().isDeferred()).isEqualTo(true);
+		@Test
+		void deferred() {
+			assertThat(getAdapter(CompletableFuture.class).getDescriptor().isDeferred()).isEqualTo(false);
+			assertThat(getAdapter(Deferred.class).getDescriptor().isDeferred()).isEqualTo(true);
+			assertThat(getAdapter(kotlinx.coroutines.flow.Flow.class).getDescriptor().isDeferred()).isEqualTo(true);
+		}
 	}
 
 	private ReactiveAdapter getAdapter(Class<?> reactiveType) {

spring-messaging/spring-messaging.gradle

@@ -26,7 +26,7 @@ dependencies {
 	testCompile("org.apache.activemq:activemq-kahadb-store")
 	testCompile("org.apache.activemq:activemq-stomp")
 	testCompile("io.projectreactor:reactor-test")
-	testCompile "io.reactivex.rxjava2:rxjava"
+	testCompile "io.reactivex.rxjava3:rxjava"
 	testCompile("org.jetbrains.kotlin:kotlin-reflect")
 	testCompile("org.jetbrains.kotlin:kotlin-stdlib")
 	testCompile("org.xmlunit:xmlunit-assertj")

spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/EncoderMethodReturnValueHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@ package org.springframework.messaging.handler.invocation.reactive;
 
 import java.util.Collections;
 
-import io.reactivex.Completable;
+import io.reactivex.rxjava3.core.Completable;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;

spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,9 +24,9 @@ import java.util.Map;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Function;
 
-import io.reactivex.Completable;
-import io.reactivex.Observable;
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Completable;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import io.rsocket.AbstractRSocket;
 import io.rsocket.Payload;
 import io.rsocket.metadata.WellKnownMimeType;

spring-web/spring-web.gradle

@@ -18,9 +18,7 @@ dependencies {
 	optional("javax.xml.bind:jaxb-api")
 	optional("javax.xml.ws:jaxws-api")
 	optional("org.glassfish.main:javax.jws")
-	optional("io.reactivex:rxjava")
-	optional("io.reactivex:rxjava-reactive-streams")
-	optional("io.reactivex.rxjava2:rxjava")
+	optional("io.reactivex.rxjava3:rxjava")
 	optional("io.netty:netty-buffer")
 	optional("io.netty:netty-handler")
 	optional("io.netty:netty-codec-http") // Until Netty4ClientHttpRequest is removed

spring-webflux/spring-webflux.gradle

@@ -16,8 +16,6 @@ dependencies {
 	optional("org.freemarker:freemarker")
 	optional("com.fasterxml.jackson.core:jackson-databind")
 	optional("com.fasterxml.jackson.dataformat:jackson-dataformat-smile")
-	optional("io.reactivex:rxjava")
-	optional("io.reactivex:rxjava-reactive-streams")
 	optional("io.projectreactor.netty:reactor-netty")
 	optional("org.apache.tomcat:tomcat-websocket")
 	optional("org.eclipse.jetty.websocket:websocket-server") {
@@ -38,7 +36,7 @@ dependencies {
 	testCompile("com.fasterxml:aalto-xml")
 	testCompile("org.hibernate:hibernate-validator")
 	testCompile("javax.validation:validation-api")
-	testCompile "io.reactivex.rxjava2:rxjava"
+	testCompile("io.reactivex.rxjava3:rxjava")
 	testCompile("io.projectreactor:reactor-test")
 	testCompile("io.undertow:undertow-core")
 	testCompile("org.apache.tomcat.embed:tomcat-embed-core")

spring-webflux/src/test/java/org/springframework/web/reactive/function/BodyInsertersTests.java

@@ -30,7 +30,7 @@ import java.util.Map;
 import java.util.Optional;
 
 import com.fasterxml.jackson.annotation.JsonView;
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/DefaultEntityResponseBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@ import java.util.EnumSet;
 import java.util.List;
 import java.util.Set;
 
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.Test;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/HttpEntityMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,16 +21,15 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 
-import io.reactivex.BackpressureStrategy;
-import io.reactivex.Flowable;
-import io.reactivex.Maybe;
+import io.reactivex.rxjava3.core.BackpressureStrategy;
+import io.reactivex.rxjava3.core.Flowable;
+import io.reactivex.rxjava3.core.Maybe;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.Observable;
-import rx.RxReactiveStreams;
-import rx.Single;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
@@ -80,12 +79,10 @@ public class HttpEntityMethodArgumentResolverTests {
 		testSupports(this.testMethod.arg(httpEntityType(String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(Mono.class, String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(Single.class, String.class)));
-		testSupports(this.testMethod.arg(httpEntityType(io.reactivex.Single.class, String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(Maybe.class, String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(CompletableFuture.class, String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(Flux.class, String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(Observable.class, String.class)));
-		testSupports(this.testMethod.arg(httpEntityType(io.reactivex.Observable.class, String.class)));
 		testSupports(this.testMethod.arg(httpEntityType(Flowable.class, String.class)));
 		testSupports(this.testMethod.arg(forClassWithGenerics(RequestEntity.class, String.class)));
 	}
@@ -132,17 +129,6 @@ public class HttpEntityMethodArgumentResolverTests {
 		ResolvableType type = httpEntityType(Single.class, String.class);
 		HttpEntity<Single<String>> entity = resolveValueWithEmptyBody(type);
 
-		StepVerifier.create(RxReactiveStreams.toPublisher(entity.getBody()))
-				.expectNextCount(0)
-				.expectError(ServerWebInputException.class)
-				.verify();
-	}
-
-	@Test
-	public void emptyBodyWithRxJava2Single() {
-		ResolvableType type = httpEntityType(io.reactivex.Single.class, String.class);
-		HttpEntity<io.reactivex.Single<String>> entity = resolveValueWithEmptyBody(type);
-
 		StepVerifier.create(entity.getBody().toFlowable())
 				.expectNextCount(0)
 				.expectError(ServerWebInputException.class)
@@ -150,7 +136,7 @@ public class HttpEntityMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void emptyBodyWithRxJava2Maybe() {
+	public void emptyBodyWithMaybe() {
 		ResolvableType type = httpEntityType(Maybe.class, String.class);
 		HttpEntity<Maybe<String>> entity = resolveValueWithEmptyBody(type);
 
@@ -165,17 +151,6 @@ public class HttpEntityMethodArgumentResolverTests {
 		ResolvableType type = httpEntityType(Observable.class, String.class);
 		HttpEntity<Observable<String>> entity = resolveValueWithEmptyBody(type);
 
-		StepVerifier.create(RxReactiveStreams.toPublisher(entity.getBody()))
-				.expectNextCount(0)
-				.expectComplete()
-				.verify();
-	}
-
-	@Test
-	public void emptyBodyWithRxJava2Observable() {
-		ResolvableType type = httpEntityType(io.reactivex.Observable.class, String.class);
-		HttpEntity<io.reactivex.Observable<String>> entity = resolveValueWithEmptyBody(type);
-
 		StepVerifier.create(entity.getBody().toFlowable(BackpressureStrategy.BUFFER))
 				.expectNextCount(0)
 				.expectComplete()
@@ -230,22 +205,12 @@ public class HttpEntityMethodArgumentResolverTests {
 		ResolvableType type = httpEntityType(Single.class, String.class);
 		HttpEntity<Single<String>> httpEntity = resolveValue(exchange, type);
 
-		assertThat(httpEntity.getHeaders()).isEqualTo(exchange.getRequest().getHeaders());
-		assertThat(httpEntity.getBody().toBlocking().value()).isEqualTo("line1");
-	}
-
-	@Test
-	public void httpEntityWithRxJava2SingleBody() {
-		ServerWebExchange exchange = postExchange("line1");
-		ResolvableType type = httpEntityType(io.reactivex.Single.class, String.class);
-		HttpEntity<io.reactivex.Single<String>> httpEntity = resolveValue(exchange, type);
-
 		assertThat(httpEntity.getHeaders()).isEqualTo(exchange.getRequest().getHeaders());
 		assertThat(httpEntity.getBody().blockingGet()).isEqualTo("line1");
 	}
 
 	@Test
-	public void httpEntityWithRxJava2MaybeBody() {
+	public void httpEntityWithMaybeBody() {
 		ServerWebExchange exchange = postExchange("line1");
 		ResolvableType type = httpEntityType(Maybe.class, String.class);
 		HttpEntity<Maybe<String>> httpEntity = resolveValue(exchange, type);
@@ -335,10 +300,8 @@ public class HttpEntityMethodArgumentResolverTests {
 			HttpEntity<Mono<String>> monoBody,
 			HttpEntity<Flux<String>> fluxBody,
 			HttpEntity<Single<String>> singleBody,
-			HttpEntity<io.reactivex.Single<String>> rxJava2SingleBody,
-			HttpEntity<Maybe<String>> rxJava2MaybeBody,
+			HttpEntity<Maybe<String>> maybeBody,
 			HttpEntity<Observable<String>> observableBody,
-			HttpEntity<io.reactivex.Observable<String>> rxJava2ObservableBody,
 			HttpEntity<Flowable<String>> flowableBody,
 			HttpEntity<CompletableFuture<String>> completableFutureBody,
 			RequestEntity<String> requestEntity,

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MessageReaderArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,15 +29,15 @@ import java.util.concurrent.CompletableFuture;
 
 import javax.xml.bind.annotation.XmlRootElement;
 
-import io.reactivex.Flowable;
-import io.reactivex.Maybe;
+import io.reactivex.rxjava3.core.Flowable;
+import io.reactivex.rxjava3.core.Maybe;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.Observable;
-import rx.Single;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
@@ -140,21 +140,11 @@ public class MessageReaderArgumentResolverTests {
 		MethodParameter param = this.testMethod.arg(type);
 		Single<TestBean> single = resolveValue(param, body);
 
-		assertThat(single.toBlocking().value()).isEqualTo(new TestBean("f1", "b1"));
-	}
-
-	@Test
-	public void rxJava2SingleTestBean() throws Exception {
-		String body = "{\"bar\":\"b1\",\"foo\":\"f1\"}";
-		ResolvableType type = forClassWithGenerics(io.reactivex.Single.class, TestBean.class);
-		MethodParameter param = this.testMethod.arg(type);
-		io.reactivex.Single<TestBean> single = resolveValue(param, body);
-
 		assertThat(single.blockingGet()).isEqualTo(new TestBean("f1", "b1"));
 	}
 
 	@Test
-	public void rxJava2MaybeTestBean() throws Exception {
+	public void maybeTestBean() throws Exception {
 		String body = "{\"bar\":\"b1\",\"foo\":\"f1\"}";
 		ResolvableType type = forClassWithGenerics(Maybe.class, TestBean.class);
 		MethodParameter param = this.testMethod.arg(type);
@@ -170,16 +160,6 @@ public class MessageReaderArgumentResolverTests {
 		MethodParameter param = this.testMethod.arg(type);
 		Observable<?> observable = resolveValue(param, body);
 
-		assertThat(observable.toList().toBlocking().first()).isEqualTo(Arrays.asList(new TestBean("f1", "b1"), new TestBean("f2", "b2")));
-	}
-
-	@Test
-	public void rxJava2ObservableTestBean() throws Exception {
-		String body = "[{\"bar\":\"b1\",\"foo\":\"f1\"},{\"bar\":\"b2\",\"foo\":\"f2\"}]";
-		ResolvableType type = forClassWithGenerics(io.reactivex.Observable.class, TestBean.class);
-		MethodParameter param = this.testMethod.arg(type);
-		io.reactivex.Observable<?> observable = resolveValue(param, body);
-
 		assertThat(observable.toList().blockingGet()).isEqualTo(Arrays.asList(new TestBean("f1", "b1"), new TestBean("f2", "b2")));
 	}
 
@@ -324,10 +304,8 @@ public class MessageReaderArgumentResolverTests {
 			@Validated Mono<TestBean> monoTestBean,
 			@Validated Flux<TestBean> fluxTestBean,
 			Single<TestBean> singleTestBean,
-			io.reactivex.Single<TestBean> rxJava2SingleTestBean,
-			Maybe<TestBean> rxJava2MaybeTestBean,
+			Maybe<TestBean> maybeTestBean,
 			Observable<TestBean> observableTestBean,
-			io.reactivex.Observable<TestBean> rxJava2ObservableTestBean,
 			Flowable<TestBean> flowableTestBean,
 			CompletableFuture<TestBean> futureTestBean,
 			TestBean testBean,

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MessageWriterResultHandlerTests.java

@@ -27,13 +27,13 @@ import java.util.List;
 
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
 import com.fasterxml.jackson.annotation.JsonTypeName;
-import io.reactivex.Flowable;
+import io.reactivex.rxjava3.core.Completable;
+import io.reactivex.rxjava3.core.Flowable;
+import io.reactivex.rxjava3.core.Observable;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.Completable;
-import rx.Observable;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.codec.ByteBufferEncoder;
@@ -117,11 +117,11 @@ public class MessageWriterResultHandlerTests {
 		testVoid(Completable.complete(), on(TestController.class).resolveReturnType(Completable.class));
 		testVoid(Observable.empty(), on(TestController.class).resolveReturnType(Observable.class, Void.class));
 
-		MethodParameter type = on(TestController.class).resolveReturnType(io.reactivex.Completable.class);
-		testVoid(io.reactivex.Completable.complete(), type);
+		MethodParameter type = on(TestController.class).resolveReturnType(Completable.class);
+		testVoid(Completable.complete(), type);
 
-		type = on(TestController.class).resolveReturnType(io.reactivex.Observable.class, Void.class);
-		testVoid(io.reactivex.Observable.empty(), type);
+		type = on(TestController.class).resolveReturnType(Observable.class, Void.class);
+		testVoid(Observable.empty(), type);
 
 		type = on(TestController.class).resolveReturnType(Flowable.class, Void.class);
 		testVoid(Flowable.empty(), type);
@@ -274,14 +274,10 @@ public class MessageWriterResultHandlerTests {
 
 		Completable completable() { return null; }
 
-		io.reactivex.Completable rxJava2Completable() { return null; }
-
 		Flux<Void> fluxVoid() { return null; }
 
 		Observable<Void> observableVoid() { return null; }
 
-		io.reactivex.Observable<Void> rxJava2ObservableVoid() { return null; }
-
 		Flowable<Void> flowableVoid() { return null; }
 
 		OutputStream outputStream() { return null; }

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelAttributeMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,12 +21,11 @@ import java.time.Duration;
 import java.util.Map;
 import java.util.function.Function;
 
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.RxReactiveStreams;
-import rx.Single;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
@@ -134,7 +133,7 @@ public class ModelAttributeMethodArgumentResolverTests {
 		testBindFoo("fooSingle", parameter, single -> {
 			boolean condition = single instanceof Single;
 			assertThat(condition).as(single.getClass().getName()).isTrue();
-			Object value = ((Single<?>) single).toBlocking().value();
+			Object value = ((Single<?>) single).blockingGet();
 			assertThat(value.getClass()).isEqualTo(Foo.class);
 			return (Foo) value;
 		});
@@ -257,7 +256,7 @@ public class ModelAttributeMethodArgumentResolverTests {
 					assertThat(value).isNotNull();
 					boolean condition = value instanceof Single;
 					assertThat(condition).isTrue();
-					return Mono.from(RxReactiveStreams.toPublisher((Single<?>) value));
+					return Mono.from(((Single<?>) value).toFlowable());
 				});
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelInitializerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,10 +23,10 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
-import rx.Single;
 
 import org.springframework.context.support.StaticApplicationContext;
 import org.springframework.core.MethodIntrospector;
@@ -122,7 +122,7 @@ public class ModelInitializerTests {
 		assertThat(((Mono<TestBean>) value).block(TIMEOUT).getName()).isEqualTo("Mono Bean");
 
 		value = model.get("singleBean");
-		assertThat(((Single<TestBean>) value).toBlocking().value().getName()).isEqualTo("Single Bean");
+		assertThat(((Single<TestBean>) value).blockingGet().getName()).isEqualTo("Single Bean");
 
 		value = model.get("voidMethodBean");
 		assertThat(((TestBean) value).getName()).isEqualTo("Void Method Bean");

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/PrincipalMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,7 @@ package org.springframework.web.reactive.result.method.annotation;
 
 import java.security.Principal;
 
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestAttributeMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package org.springframework.web.reactive.result.method.annotation;
 import java.time.Duration;
 import java.util.Optional;
 
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestBodyMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,15 +22,15 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 
-import io.reactivex.Maybe;
+import io.reactivex.rxjava3.core.BackpressureStrategy;
+import io.reactivex.rxjava3.core.Maybe;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.Observable;
-import rx.RxReactiveStreams;
-import rx.Single;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
@@ -150,14 +150,14 @@ public class RequestBodyMethodArgumentResolverTests {
 	public void emptyBodyWithSingle() {
 		MethodParameter param = this.testMethod.annot(requestBody()).arg(Single.class, String.class);
 		Single<String> single = resolveValueWithEmptyBody(param);
-		StepVerifier.create(RxReactiveStreams.toPublisher(single))
+		StepVerifier.create(single.toFlowable())
 				.expectNextCount(0)
 				.expectError(ServerWebInputException.class)
 				.verify();
 
 		param = this.testMethod.annot(requestBody().notRequired()).arg(Single.class, String.class);
 		single = resolveValueWithEmptyBody(param);
-		StepVerifier.create(RxReactiveStreams.toPublisher(single))
+		StepVerifier.create(single.toFlowable())
 				.expectNextCount(0)
 				.expectError(ServerWebInputException.class)
 				.verify();
@@ -184,14 +184,14 @@ public class RequestBodyMethodArgumentResolverTests {
 	public void emptyBodyWithObservable() {
 		MethodParameter param = this.testMethod.annot(requestBody()).arg(Observable.class, String.class);
 		Observable<String> observable = resolveValueWithEmptyBody(param);
-		StepVerifier.create(RxReactiveStreams.toPublisher(observable))
+		StepVerifier.create(observable.toFlowable(BackpressureStrategy.BUFFER))
 				.expectNextCount(0)
 				.expectError(ServerWebInputException.class)
 				.verify();
 
 		param = this.testMethod.annot(requestBody().notRequired()).arg(Observable.class, String.class);
 		observable = resolveValueWithEmptyBody(param);
-		StepVerifier.create(RxReactiveStreams.toPublisher(observable))
+		StepVerifier.create(observable.toFlowable(BackpressureStrategy.BUFFER))
 				.expectNextCount(0)
 				.expectComplete()
 				.verify();
@@ -248,19 +248,15 @@ public class RequestBodyMethodArgumentResolverTests {
 			@RequestBody Mono<String> mono,
 			@RequestBody Flux<String> flux,
 			@RequestBody Single<String> single,
-			@RequestBody io.reactivex.Single<String> rxJava2Single,
-			@RequestBody Maybe<String> rxJava2Maybe,
-			@RequestBody Observable<String> obs,
-			@RequestBody io.reactivex.Observable<String> rxjava2Obs,
+			@RequestBody Maybe<String> maybe,
+			@RequestBody Observable<String> observable,
 			@RequestBody CompletableFuture<String> future,
 			@RequestBody(required = false) String stringNotRequired,
 			@RequestBody(required = false) Mono<String> monoNotRequired,
 			@RequestBody(required = false) Flux<String> fluxNotRequired,
 			@RequestBody(required = false) Single<String> singleNotRequired,
-			@RequestBody(required = false) io.reactivex.Single<String> rxJava2SingleNotRequired,
-			@RequestBody(required = false) Maybe<String> rxJava2MaybeNotRequired,
-			@RequestBody(required = false) Observable<String> obsNotRequired,
-			@RequestBody(required = false) io.reactivex.Observable<String> rxjava2ObsNotRequired,
+			@RequestBody(required = false) Maybe<String> maybeNotRequired,
+			@RequestBody(required = false) Observable<String> observableNotRequired,
 			@RequestBody(required = false) CompletableFuture<String> futureNotRequired,
 			@RequestBody(required = false) Map<?, ?> mapNotRequired,
 			String notAnnotated) {}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestMappingMessageConversionIntegrationTests.java

@@ -26,14 +26,14 @@ import java.util.concurrent.CompletableFuture;
 import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
 
-import io.reactivex.Flowable;
-import io.reactivex.Maybe;
+import io.reactivex.rxjava3.core.Completable;
+import io.reactivex.rxjava3.core.Flowable;
+import io.reactivex.rxjava3.core.Maybe;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
-import rx.Completable;
-import rx.Observable;
-import rx.Single;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -118,15 +118,7 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		startServer(httpServer);
 
 		String expected = "Hello!";
-		assertThat(performGet("/raw-response/observable", new HttpHeaders(), String.class).getBody()).isEqualTo(expected);
-	}
-
-	@ParameterizedHttpServerTest
-	public void byteBufferResponseBodyWithRxJava2Observable(HttpServer httpServer) throws Exception {
-		startServer(httpServer);
-
-		String expected = "Hello!";
-		assertThat(performGet("/raw-response/rxjava2-observable",
+		assertThat(performGet("/raw-response/observable",
 				new HttpHeaders(), String.class).getBody()).isEqualTo(expected);
 	}
 
@@ -317,18 +309,10 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 	}
 
 	@ParameterizedHttpServerTest
-	public void personTransformWithRxJava2Single(HttpServer httpServer) throws Exception {
+	public void personTransformWithMaybe(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
 
-		assertThat(performPost("/person-transform/rxjava2-single", JSON, new Person("Robert"),
-				JSON, Person.class).getBody()).isEqualTo(new Person("ROBERT"));
-	}
-
-	@ParameterizedHttpServerTest
-	public void personTransformWithRxJava2Maybe(HttpServer httpServer) throws Exception {
-		startServer(httpServer);
-
-		assertThat(performPost("/person-transform/rxjava2-maybe", JSON, new Person("Robert"),
+		assertThat(performPost("/person-transform/maybe", JSON, new Person("Robert"),
 				JSON, Person.class).getBody()).isEqualTo(new Person("ROBERT"));
 	}
 
@@ -359,15 +343,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		assertThat(performPost("/person-transform/observable", JSON, req, JSON, PERSON_LIST).getBody()).isEqualTo(res);
 	}
 
-	@ParameterizedHttpServerTest
-	public void personTransformWithRxJava2Observable(HttpServer httpServer) throws Exception {
-		startServer(httpServer);
-
-		List<?> req = asList(new Person("Robert"), new Person("Marie"));
-		List<?> res = asList(new Person("ROBERT"), new Person("MARIE"));
-		assertThat(performPost("/person-transform/rxjava2-observable", JSON, req, JSON, PERSON_LIST).getBody()).isEqualTo(res);
-	}
-
 	@ParameterizedHttpServerTest
 	public void personTransformWithFlowable(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
@@ -421,17 +396,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		assertThat(getApplicationContext().getBean(PersonCreateController.class).persons.size()).isEqualTo(1);
 	}
 
-	@ParameterizedHttpServerTest
-	public void personCreateWithRxJava2Single(HttpServer httpServer) throws Exception {
-		startServer(httpServer);
-
-		ResponseEntity<Void> entity = performPost(
-				"/person-create/rxjava2-single", JSON, new Person("Robert"), null, Void.class);
-
-		assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
-		assertThat(getApplicationContext().getBean(PersonCreateController.class).persons.size()).isEqualTo(1);
-	}
-
 	@ParameterizedHttpServerTest
 	public void personCreateWithFluxJson(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
@@ -465,17 +429,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		assertThat(getApplicationContext().getBean(PersonCreateController.class).persons.size()).isEqualTo(2);
 	}
 
-	@ParameterizedHttpServerTest
-	public void personCreateWithRxJava2ObservableJson(HttpServer httpServer) throws Exception {
-		startServer(httpServer);
-
-		ResponseEntity<Void> entity = performPost("/person-create/rxjava2-observable", JSON,
-				asList(new Person("Robert"), new Person("Marie")), null, Void.class);
-
-		assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
-		assertThat(getApplicationContext().getBean(PersonCreateController.class).persons.size()).isEqualTo(2);
-	}
-
 	@ParameterizedHttpServerTest
 	public void personCreateWithObservableXml(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
@@ -487,18 +440,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		assertThat(getApplicationContext().getBean(PersonCreateController.class).persons.size()).isEqualTo(2);
 	}
 
-	@ParameterizedHttpServerTest
-	public void personCreateWithRxJava2ObservableXml(HttpServer httpServer) throws Exception {
-		startServer(httpServer);
-
-		People people = new People(new Person("Robert"), new Person("Marie"));
-		String url = "/person-create/rxjava2-observable";
-		ResponseEntity<Void> response = performPost(url, APPLICATION_XML, people, null, Void.class);
-
-		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
-		assertThat(getApplicationContext().getBean(PersonCreateController.class).persons.size()).isEqualTo(2);
-	}
-
 	@ParameterizedHttpServerTest
 	public void personCreateWithFlowableJson(HttpServer httpServer) throws Exception {
 		startServer(httpServer);
@@ -567,11 +508,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 			return Observable.just(ByteBuffer.wrap("Hello!".getBytes()));
 		}
 
-		@GetMapping("/rxjava2-observable")
-		public io.reactivex.Observable<ByteBuffer> getRxJava2Observable() {
-			return io.reactivex.Observable.just(ByteBuffer.wrap("Hello!".getBytes()));
-		}
-
 		@GetMapping("/flowable")
 		public Flowable<ByteBuffer> getFlowable() {
 			return Flowable.just(ByteBuffer.wrap("Hello!".getBytes()));
@@ -670,9 +606,8 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		}
 
 		@PostMapping("/completable-future")
-		public CompletableFuture<Person> transformCompletableFuture(
-				@RequestBody CompletableFuture<Person> personFuture) {
-			return personFuture.thenApply(person -> new Person(person.getName().toUpperCase()));
+		public CompletableFuture<Person> transformCompletableFuture(@RequestBody CompletableFuture<Person> future) {
+			return future.thenApply(person -> new Person(person.getName().toUpperCase()));
 		}
 
 		@PostMapping("/mono")
@@ -685,21 +620,14 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 			return personFuture.map(person -> new Person(person.getName().toUpperCase()));
 		}
 
-		@PostMapping("/rxjava2-single")
-		public io.reactivex.Single<Person> transformRxJava2Single(@RequestBody io.reactivex.Single<Person> personFuture) {
-			return personFuture.map(person -> new Person(person.getName().toUpperCase()));
-		}
-
-		@PostMapping("/rxjava2-maybe")
-		public Maybe<Person> transformRxJava2Maybe(@RequestBody Maybe<Person> personFuture) {
+		@PostMapping("/maybe")
+		public Maybe<Person> transformMaybe(@RequestBody Maybe<Person> personFuture) {
 			return personFuture.map(person -> new Person(person.getName().toUpperCase()));
 		}
 
 		@PostMapping("/publisher")
 		public Publisher<Person> transformPublisher(@RequestBody Publisher<Person> persons) {
-			return Flux
-					.from(persons)
-					.map(person -> new Person(person.getName().toUpperCase()));
+			return Flux.from(persons).map(person -> new Person(person.getName().toUpperCase()));
 		}
 
 		@PostMapping("/flux")
@@ -712,11 +640,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 			return persons.map(person -> new Person(person.getName().toUpperCase()));
 		}
 
-		@PostMapping("/rxjava2-observable")
-		public io.reactivex.Observable<Person> transformObservable(@RequestBody io.reactivex.Observable<Person> persons) {
-			return persons.map(person -> new Person(person.getName().toUpperCase()));
-		}
-
 		@PostMapping("/flowable")
 		public Flowable<Person> transformFlowable(@RequestBody Flowable<Person> persons) {
 			return persons.map(person -> new Person(person.getName().toUpperCase()));
@@ -743,11 +666,6 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 
 		@PostMapping("/single")
 		public Completable createWithSingle(@RequestBody Single<Person> single) {
-			return single.map(persons::add).toCompletable();
-		}
-
-		@PostMapping("/rxjava2-single")
-		public io.reactivex.Completable createWithRxJava2Single(@RequestBody io.reactivex.Single<Person> single) {
 			return single.map(persons::add).ignoreElement();
 		}
 
@@ -757,19 +675,12 @@ public class RequestMappingMessageConversionIntegrationTests extends AbstractReq
 		}
 
 		@PostMapping("/observable")
-		public Observable<Void> createWithObservable(@RequestBody Observable<Person> observable) {
-			return observable.toList().doOnNext(persons::addAll).flatMap(document -> Observable.empty());
-		}
-
-		@PostMapping("/rxjava2-observable")
-		public io.reactivex.Completable createWithRxJava2Observable(
-				@RequestBody io.reactivex.Observable<Person> observable) {
-
+		public Completable createWithObservable(@RequestBody Observable<Person> observable) {
 			return observable.toList().doOnSuccess(persons::addAll).ignoreElement();
 		}
 
 		@PostMapping("/flowable")
-		public io.reactivex.Completable createWithFlowable(@RequestBody Flowable<Person> flowable) {
+		public Completable createWithFlowable(@RequestBody Flowable<Person> flowable) {
 			return flowable.toList().doOnSuccess(persons::addAll).ignoreElement();
 		}
 	}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseBodyResultHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,11 +20,11 @@ import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
 
+import io.reactivex.rxjava3.core.Completable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
-import rx.Completable;
-import rx.Single;
 
 import org.springframework.core.codec.ByteBufferEncoder;
 import org.springframework.core.codec.CharSequenceEncoder;

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandlerTests.java

@@ -28,13 +28,13 @@ import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 
+import io.reactivex.rxjava3.core.Completable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.Completable;
-import rx.Single;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/WebSessionMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +15,7 @@
  */
 package org.springframework.web.reactive.result.method.annotation;
 
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/view/AbstractViewTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,8 +21,8 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 
-import io.reactivex.Observable;
-import io.reactivex.Single;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.core.Single;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;

spring-webflux/src/test/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandlerTests.java

@@ -26,11 +26,11 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.TreeMap;
 
+import io.reactivex.rxjava3.core.Completable;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
-import rx.Completable;
 
 import org.springframework.context.support.StaticApplicationContext;
 import org.springframework.core.MethodParameter;

spring-webflux/src/test/kotlin/org/springframework/web/reactive/function/server/ServerResponseExtensionsTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package org.springframework.web.reactive.function.server
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
-import io.reactivex.Flowable
+import io.reactivex.rxjava3.core.Flowable
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.runBlocking
 import org.assertj.core.api.Assertions.assertThat

spring-webmvc/spring-webmvc.gradle

@@ -59,9 +59,7 @@ dependencies {
 	testCompile("org.hibernate:hibernate-validator")
 	testCompile("javax.validation:validation-api")
 	testCompile("io.projectreactor:reactor-core")
-	testCompile("io.reactivex:rxjava")
-	testCompile("io.reactivex:rxjava-reactive-streams")
-	testCompile("io.reactivex.rxjava2:rxjava")
+	testCompile("io.reactivex.rxjava3:rxjava")
 	testCompile("org.jetbrains.kotlin:kotlin-script-runtime")
 	testRuntime("org.jetbrains.kotlin:kotlin-scripting-jsr223-embeddable")
 	testRuntime("org.jruby:jruby")

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ReactiveTypeHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,14 +26,14 @@ import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
+import io.reactivex.rxjava3.core.Single;
+import io.reactivex.rxjava3.core.SingleEmitter;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.EmitterProcessor;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.core.publisher.MonoProcessor;
-import rx.Single;
-import rx.SingleEmitter;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
@@ -98,7 +98,6 @@ public class ReactiveTypeHandlerTests {
 	public void supportsType() throws Exception {
 		assertThat(this.handler.isReactiveType(Mono.class)).isTrue();
 		assertThat(this.handler.isReactiveType(Single.class)).isTrue();
-		assertThat(this.handler.isReactiveType(io.reactivex.Single.class)).isTrue();
 	}
 
 	@Test
@@ -117,16 +116,10 @@ public class ReactiveTypeHandlerTests {
 		MonoProcessor<String> monoEmpty = MonoProcessor.create();
 		testDeferredResultSubscriber(monoEmpty, Mono.class, forClass(String.class), monoEmpty::onComplete, null);
 
-		// RxJava 1 Single
-		AtomicReference<SingleEmitter<String>> ref = new AtomicReference<>();
-		Single<String> single = Single.fromEmitter(ref::set);
-		testDeferredResultSubscriber(single, Single.class, forClass(String.class),
-				() -> ref.get().onSuccess("foo"), "foo");
-
-		// RxJava 2 Single
-		AtomicReference<io.reactivex.SingleEmitter<String>> ref2 = new AtomicReference<>();
-		io.reactivex.Single<String> single2 = io.reactivex.Single.create(ref2::set);
-		testDeferredResultSubscriber(single2, io.reactivex.Single.class, forClass(String.class),
+		// RxJava Single
+		AtomicReference<SingleEmitter<String>> ref2 = new AtomicReference<>();
+		Single<String> single2 = Single.create(ref2::set);
+		testDeferredResultSubscriber(single2, Single.class, forClass(String.class),
 				() -> ref2.get().onSuccess("foo"), "foo");
 	}
 
@@ -162,15 +155,10 @@ public class ReactiveTypeHandlerTests {
 		MonoProcessor<String> mono = MonoProcessor.create();
 		testDeferredResultSubscriber(mono, Mono.class, forClass(String.class), () -> mono.onError(ex), ex);
 
-		// RxJava 1 Single
-		AtomicReference<SingleEmitter<String>> ref = new AtomicReference<>();
-		Single<String> single = Single.fromEmitter(ref::set);
-		testDeferredResultSubscriber(single, Single.class, forClass(String.class), () -> ref.get().onError(ex), ex);
-
-		// RxJava 2 Single
-		AtomicReference<io.reactivex.SingleEmitter<String>> ref2 = new AtomicReference<>();
-		io.reactivex.Single<String> single2 = io.reactivex.Single.create(ref2::set);
-		testDeferredResultSubscriber(single2, io.reactivex.Single.class, forClass(String.class),
+		// RxJava Single
+		AtomicReference<SingleEmitter<String>> ref2 = new AtomicReference<>();
+		Single<String> single2 = Single.create(ref2::set);
+		testDeferredResultSubscriber(single2, Single.class, forClass(String.class),
 				() -> ref2.get().onError(ex), ex);
 	}
 
@@ -343,8 +331,6 @@ public class ReactiveTypeHandlerTests {
 
 		Single<String> handleSingle() { return null; }
 
-		io.reactivex.Single<String> handleSingleRxJava2() { return null; }
-
 		Flux<Bar> handleFlux() { return null; }
 
 		Flux<String> handleFluxString() { return null; }