Merge branch '5.3.x'

# Conflicts:
#	spring-context/spring-context.gradle
#	spring-core/src/main/java/org/springframework/core/ReactiveAdapterRegistry.java

spring-core/src/main/java/org/springframework/asm/ClassReader.java

@@ -324,7 +324,9 @@ public class ClassReader {
       }
       outputStream.flush();
       if (readCount == 1) {
-        return data;
+        // SPRING PATCH: some misbehaving InputStreams return -1 but still write to buffer (gh-27429)
+        // return data;
+        // END OF PATCH
       }
       return outputStream.toByteArray();
     } finally {

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

@@ -275,6 +275,7 @@ public class ReactiveAdapterRegistry {
 		}
 	}
 
+
 	private static class RxJava3Registrar {
 
 		void registerAdapters(ReactiveAdapterRegistry registry) {