Merge pull request #22214 from XenoAmess

* gh-22214:
  Polish "Fix unwrapping of captured PrintStream in test support's OutputCapture"
  Fix unwrapping of captured PrintStream in test support's OutputCapture

Closes gh-22214

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/system/OutputCapture.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -194,7 +194,7 @@ class OutputCapture implements CapturedOutput {
 
 		private static PrintStream getSystemStream(PrintStream printStream) {
 			while (printStream instanceof PrintStreamCapture) {
-				return ((PrintStreamCapture) printStream).getParent();
+				printStream = ((PrintStreamCapture) printStream).getParent();
 			}
 			return printStream;
 		}