[java] fix missing dependency check in the Maven tests (#1674)
[java] fix missing dependency check in the Maven tests (#1674)

Summary:
The variable `SOURCES` was not defined, which means that changing the Java sources would not trigger the test if those had already been run before.

Without these changes, one could run:
```
$ make build_mvn_test
```
change the Java source file in a way that would change the list of Infer warnings, then, run again:
```
make build_mvn_test
```
and the test would still pass. This pull request fixes this.

All the tests are passing after the changes using `make -j test`.

Pull Request resolved: https://github.com/facebook/infer/pull/1674

Reviewed By: dulmarod

Differential Revision: D39430723

Pulled By: jvillard

fbshipit-source-id: c2078e4279384978f54a00156399776b8a71c1fe

facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer