Fix findbugs violations in library

Fix findbugs violations in library

- Possible null pointer dereference
- Equals method should not assume anything about the type of its argument
- Method ignores exceptional return value
- Equals checks for incompatible operand
- Unusual equals method
- Class is Serializable, but doesn't define serialVersionUID
- Consider using Locale parameterized version of invoked method
- Field isn't final but should be
- Incorrect lazy initialization of static field
- Inefficient use of keySet iterator instead of entrySet iterator
- Should be a static inner class
- Boxing/unboxing to parse a primitive
- Unread field
- Return value of method without side effect is ignored
- Write to static field from instance method
- Load of known null value

Change-Id: I5f7ae7b280919d2f1cfcd86be41cab5d8370a752
Signed-off-by: Tom Pantelis <tompantelis@gmail.com>