The test/jdk/java/util/jar/JarFile/mrjar/MultiReleaseJarAPI.java test has a commented out line which tests for the "Multi-Release" attribute's value, when the value uses the "\r" newline character. It was commented in the test due to a bug in Manifest parsing as noted in https://bugs.openjdk.org/browse/JDK-8176843.
That bug has been fixed several releases back through https://bugs.openjdk.org/browse/JDK-8200530. The commented out line in test/jdk/java/util/jar/JarFile/mrjar/MultiReleaseJarAPI.java should now be uncommented to allow it to test the usage of "\r" newline character.