[Checkers] NonNull assertions

[Mahmood Ali]

Greetings,

This may not be relevant to this paper.  However, I wanted to bring it  
up for future reference.

In my case studies,  I have noticed that many projects have their own  
method of asserting (non-)null-ability.

- Eclipse has Assert.nonNull()
- Google Guice has Objects.nonNull() and ensureNonNull() to assert  
nonnullability
- Javac tends to start calling getClass() on parameters as the first  
statements in the method declaration block.

Regards,
Mahmood