I'm more familiar with TestNG, but I see that some of the existing test have things like this:

@Test(expected=NullPointerException.class)

Is it possible to use the same notation for your tests with Junit? In TestNG I know you can't specify the message expected, but maybe JUnit lets you? It would make the test cases simpler if you could.

--EDIT

Regardless, these look good and appear to cover the use cases of the code change. I don't see any need to change them except possibly for readability.

I'm not as familiar with JUnit either, so I'll follow whatever convention you prefer (I just tried to copy what I already saw in the CDL tests).

Aside from the test cases that are expecting to generate a NullPointerException, I only saw "@test" used. For that reason, I only prefaced each test case with "@test". What convention do you have in mind as an alternative?

Looks good, thanks for taking the time to do the unit tests. Either style for catching exceptions is acceptable. Will merge after the JSON-Java change is accepted.