Upgrade to Reactor 2020.0-RC2

See gh-25884

build.gradle

@@ -27,7 +27,7 @@ configure(allprojects) { project ->
 		imports {
 			mavenBom "com.fasterxml.jackson:jackson-bom:2.11.3"
 			mavenBom "io.netty:netty-bom:4.1.52.Final"
-			mavenBom "io.projectreactor:reactor-bom:2020.0.0-SNAPSHOT"
+			mavenBom "io.projectreactor:reactor-bom:2020.0.0-RC2"
 			mavenBom "io.r2dbc:r2dbc-bom:Arabba-SR7"
 			mavenBom "io.rsocket:rsocket-bom:1.1.0-M2"
 			mavenBom "org.eclipse.jetty:jetty-bom:9.4.31.v20200723"
@@ -291,7 +291,7 @@ configure(allprojects) { project ->
 		repositories {
 			mavenCentral()
 			maven { url "https://repo.spring.io/libs-spring-framework-build" }
-			maven { url "https://repo.spring.io/snapshot" } // Reactor
+			maven { url "https://repo.spring.io/milestone" } // Reactor
 		}
 	}
 	configurations.all {

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

@@ -25,8 +25,8 @@ import kotlinx.coroutines.Deferred;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.reactivestreams.Publisher;
+import reactor.core.CoreSubscriber;
 import reactor.core.publisher.Flux;
-import reactor.core.publisher.FluxProcessor;
 import reactor.core.publisher.Mono;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -45,16 +45,16 @@ class ReactiveAdapterRegistryTests {
 	void getAdapterForReactiveSubType() {
 
 		ReactiveAdapter adapter1 = getAdapter(Flux.class);
-		ReactiveAdapter adapter2 = getAdapter(FluxProcessor.class);
+		ReactiveAdapter adapter2 = getAdapter(ExtendedFlux.class);
 
 		assertThat(adapter2).isSameAs(adapter1);
 
 		this.registry.registerReactiveType(
-				ReactiveTypeDescriptor.multiValue(FluxProcessor.class, FluxProcessor::empty),
+				ReactiveTypeDescriptor.multiValue(ExtendedFlux.class, ExtendedFlux::empty),
-				o -> (FluxProcessor<?, ?>) o,
+				o -> (ExtendedFlux<?>) o,
-				FluxProcessor::from);
+				ExtendedFlux::from);
 
-		ReactiveAdapter adapter3 = getAdapter(FluxProcessor.class);
+		ReactiveAdapter adapter3 = getAdapter(ExtendedFlux.class);
 
 		assertThat(adapter3).isNotNull();
 		assertThat(adapter3).isNotSameAs(adapter1);
@@ -363,4 +363,12 @@ class ReactiveAdapterRegistryTests {
 		return adapter;
 	}
 
+
+	private static class ExtendedFlux<T> extends Flux<T> {
+
+		@Override
+		public void subscribe(CoreSubscriber actual) {
+			throw new UnsupportedOperationException();
+		}
+	}
 }