Javadoc tweaks.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1519727 13f79535-47bb-0310-9956-ffa450edef68
No need to initialize an ivar decl to null.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1519728 13f79535-47bb-0310-9956-ffa450edef68