Fix missing end tag.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621033 13f79535-47bb-0310-9956-ffa450edef68
Simplify null check. The string is never nul.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621034 13f79535-47bb-0310-9956-ffa450edef68
Add missing </p> tags.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621035 13f79535-47bb-0310-9956-ffa450edef68
Add missing </p> tags.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621036 13f79535-47bb-0310-9956-ffa450edef68
Convert Constants into an interface.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621037 13f79535-47bb-0310-9956-ffa450edef68
Fix javadoc markup.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621038 13f79535-47bb-0310-9956-ffa450edef68
Add missing tags.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1621039 13f79535-47bb-0310-9956-ffa450edef68