Add documentation requiring non-null values.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597362 13f79535-47bb-0310-9956-ffa450edef68
Add @Documented to annotations.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597363 13f79535-47bb-0310-9956-ffa450edef68
Add annotations to PluginDefault annotation.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597364 13f79535-47bb-0310-9956-ffa450edef68
Add default values for type conversion.

  - Part of LOG4J2-652.
  - Related to LOG4J2-598.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597365 13f79535-47bb-0310-9956-ffa450edef68
Add type checking for Node and Configuration assignment.

  - This will help prevent runtime reflection exceptions when calling the plugin factory method. Instead, an error message is logged by StatusLogger.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597366 13f79535-47bb-0310-9956-ffa450edef68
Add type conversion for Charset class.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597368 13f79535-47bb-0310-9956-ffa450edef68
Add changelog entries for 598 and 652.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1597370 13f79535-47bb-0310-9956-ffa450edef68