Simplification: try to be less surprising to the users:
- Getter methods clone the returned array, like what many libraries do.
- If no value (i.e. setValue(null) is invoked), unconditionally use the default value. Do not check anymore if the parameter is mandatory or optional.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1567042 13f79535-47bb-0310-9956-ffa450edef68