Polishing

spring-context/spring-context.gradle

@@ -34,8 +34,8 @@ dependencies {
 	testImplementation("org.codehaus.groovy:groovy-test")
 	testImplementation("org.codehaus.groovy:groovy-xml")
 	testImplementation("org.apache.commons:commons-pool2")
-	testImplementation("javax.inject:javax.inject-tck")
 	testImplementation("org.awaitility:awaitility")
+	testImplementation("javax.inject:javax.inject-tck")
 	testRuntimeOnly("javax.xml.bind:jaxb-api")
 	testRuntimeOnly("org.glassfish:javax.el")
 	// Substitute for javax.management:jmxremote_optional:1.0.1_04 (not available on Maven Central)

spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostConstructAndAutowiringTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -25,7 +25,6 @@ import org.springframework.beans.testfixture.beans.TestBean;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-
 /**
  * Tests cornering the issue reported in SPR-8080. If the product of a @Bean method
  * was @Autowired into a configuration class while at the same time the declaring
@@ -34,7 +33,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * 'currently in creation' status of the autowired bean and result in creating multiple
  * instances of the given @Bean, violating container scoping / singleton semantics.
  *
- * This is resolved through no longer relying on 'currently in creation' status, but
+ * <p>This is resolved through no longer relying on 'currently in creation' status, but
  * rather on a thread local that informs the enhanced bean method implementation whether
  * the factory is the caller or not.
  *

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

@@ -77,11 +77,11 @@ public class ReactiveAdapterRegistry {
 	static {
 		ClassLoader classLoader = ReactiveAdapterRegistry.class.getClassLoader();
 		reactorPresent = ClassUtils.isPresent("reactor.core.publisher.Flux", classLoader);
+		flowPublisherPresent = ClassUtils.isPresent("java.util.concurrent.Flow.Publisher", classLoader);
 		rxjava1Present = ClassUtils.isPresent("rx.Observable", classLoader) &&
 				ClassUtils.isPresent("rx.RxReactiveStreams", classLoader);
 		rxjava2Present = ClassUtils.isPresent("io.reactivex.Flowable", classLoader);
 		rxjava3Present = ClassUtils.isPresent("io.reactivex.rxjava3.core.Flowable", classLoader);
-		flowPublisherPresent = ClassUtils.isPresent("java.util.concurrent.Flow.Publisher", classLoader);
 		kotlinCoroutinesPresent = ClassUtils.isPresent("kotlinx.coroutines.reactor.MonoKt", classLoader);
 		mutinyPresent = ClassUtils.isPresent("io.smallrye.mutiny.Multi", classLoader);
 	}
@@ -97,13 +97,16 @@ public class ReactiveAdapterRegistry {
 		// Reactor
 		if (reactorPresent) {
 			new ReactorRegistrar().registerAdapters(this);
+			if (flowPublisherPresent) {
+				// Java 9+ Flow.Publisher
+				new ReactorJdkFlowAdapterRegistrar().registerAdapter(this);
+			}
 		}
 
 		// RxJava1 (deprecated)
 		if (rxjava1Present) {
 			new RxJava1Registrar().registerAdapters(this);
 		}
-
 		// RxJava2
 		if (rxjava2Present) {
 			new RxJava2Registrar().registerAdapters(this);
@@ -113,13 +116,6 @@ public class ReactiveAdapterRegistry {
 			new RxJava3Registrar().registerAdapters(this);
 		}
 
-		// Java 9+ Flow.Publisher
-		if (flowPublisherPresent) {
-			new ReactorJdkFlowAdapterRegistrar().registerAdapter(this);
-		}
-		// If not present, do nothing for the time being...
-		// We can fall back on "reactive-streams-flow-bridge" (once released)
-
 		// Kotlin Coroutines
 		if (reactorPresent && kotlinCoroutinesPresent) {
 			new CoroutinesRegistrar().registerAdapters(this);
@@ -253,6 +249,35 @@ public class ReactiveAdapterRegistry {
 	}
 
 
+	private static class ReactorJdkFlowAdapterRegistrar {
+
+		void registerAdapter(ReactiveAdapterRegistry registry) {
+			// Reflectively access optional JDK 9+ API (for runtime compatibility with JDK 8)
+
+			try {
+				String publisherName = "java.util.concurrent.Flow.Publisher";
+				Class<?> publisherClass = ClassUtils.forName(publisherName, getClass().getClassLoader());
+
+				String adapterName = "reactor.adapter.JdkFlowAdapter";
+				Class<?> flowAdapterClass = ClassUtils.forName(adapterName,  getClass().getClassLoader());
+
+				Method toFluxMethod = flowAdapterClass.getMethod("flowPublisherToFlux", publisherClass);
+				Method toFlowMethod = flowAdapterClass.getMethod("publisherToFlowPublisher", Publisher.class);
+				Object emptyFlow = ReflectionUtils.invokeMethod(toFlowMethod, null, Flux.empty());
+
+				registry.registerReactiveType(
+						ReactiveTypeDescriptor.multiValue(publisherClass, () -> emptyFlow),
+						source -> (Publisher<?>) ReflectionUtils.invokeMethod(toFluxMethod, null, source),
+						publisher -> ReflectionUtils.invokeMethod(toFlowMethod, null, publisher)
+				);
+			}
+			catch (Throwable ex) {
+				// Ignore
+			}
+		}
+	}
+
+
 	private static class RxJava1Registrar {
 
 		void registerAdapters(ReactiveAdapterRegistry registry) {
@@ -307,6 +332,7 @@ public class ReactiveAdapterRegistry {
 		}
 	}
 
+
 	private static class RxJava3Registrar {
 
 		void registerAdapters(ReactiveAdapterRegistry registry) {
@@ -347,34 +373,6 @@ public class ReactiveAdapterRegistry {
 		}
 	}
 
-	private static class ReactorJdkFlowAdapterRegistrar {
-
-		void registerAdapter(ReactiveAdapterRegistry registry) {
-			// TODO: remove reflection when build requires JDK 9+
-
-			try {
-				String publisherName = "java.util.concurrent.Flow.Publisher";
-				Class<?> publisherClass = ClassUtils.forName(publisherName, getClass().getClassLoader());
-
-				String adapterName = "reactor.adapter.JdkFlowAdapter";
-				Class<?> flowAdapterClass = ClassUtils.forName(adapterName,  getClass().getClassLoader());
-
-				Method toFluxMethod = flowAdapterClass.getMethod("flowPublisherToFlux", publisherClass);
-				Method toFlowMethod = flowAdapterClass.getMethod("publisherToFlowPublisher", Publisher.class);
-				Object emptyFlow = ReflectionUtils.invokeMethod(toFlowMethod, null, Flux.empty());
-
-				registry.registerReactiveType(
-						ReactiveTypeDescriptor.multiValue(publisherClass, () -> emptyFlow),
-						source -> (Publisher<?>) ReflectionUtils.invokeMethod(toFluxMethod, null, source),
-						publisher -> ReflectionUtils.invokeMethod(toFlowMethod, null, publisher)
-				);
-			}
-			catch (Throwable ex) {
-				// Ignore
-			}
-		}
-	}
-
 
 	/**
 	 * ReactiveAdapter variant that wraps adapted Publishers as {@link Flux} or