Adds getModuleId method as a fallback when getJarLocation is null at

[Otávio Gonçalves de Santana]

It PR adds the getModuleId method as a fallback when getJarLocation is null
at CmpJpaConversion, this way it keeps the desired behavior and fixes the
when the getJarLocation is null such as the CheckMissingClassTest.

https://github.com/apache/tomee/pull/274