Add arguments validation to Java APIs.

Add arguments validation to Java APIs.

[Problem] There are not arguments validation in some Java APIs.
[Solution] Add null-checks and other validation logics to Java APIs.

* Add exceptions to Java class constructors.

* Synchronize the return type of setEventListener.

* Synchronize return types of Java functions.

* Add instance null-checkings to all Java APIs.

* Apply NonNull annotation.

* Apply PowerMock to handle static initialization blocks.

Change-Id: I978e78ab2028a0acdfdf1cf398485ffd81e5db89