OGM-283 Add checkstyle rule: RedundantModifier

 Checks for redundant modifiers in:

 1. interface and annotation definitions,
 2. the final modifier on methods of final classes, and
 3. inner interface declarations that are declared as static

 Rationale: The Java Language Specification strongly
 discourages the usage of "public" and "abstract" for method
 declarations in interface definitions as a matter of style.

 Variables in interfaces and annotations are automatically
 public, static and final, so these modifiers are redundant
 as well.

 As annotations are a form of interface, their fields are
 also automatically public, static and final just as their
 annotation fields are automatically public and abstract.

 Final classes by definition can not be extended so the
 final modifier on the method of a final class is redundant.
OGM-283 Fix checkstyle violations for RedundantModifer