Add nullability annotations to tests in module/spring-boot-rsocket-test

See gh-47263

module/spring-boot-rsocket-test/build.gradle

@@ -33,3 +33,7 @@ dependencies {
 
 	testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

module/spring-boot-rsocket-test/src/test/java/org/springframework/boot/test/rsocket/server/LocalRSocketServerPortTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.test.rsocket.server;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 
@@ -37,10 +38,10 @@ import static org.assertj.core.api.Assertions.assertThat;
 class LocalRSocketServerPortTests {
 
 	@Value("${local.rsocket.server.port}")
-	private String fromValue;
+	private @Nullable String fromValue;
 
 	@LocalRSocketServerPort
-	private String fromAnnotation;
+	private @Nullable String fromAnnotation;
 
 	@Test
 	void testLocalRSocketServerPortAnnotation() {