make sure sonar or compiler fails on warnings about pdengine

[szirbucz]

@magwas Are compiler warnings enough or do we need Unused import, Unused local variable, etc... (What currently Eclipse crying for)
For the second one, I guess we need CheckStyle.

[magwas]

Either the CI build should fail or Sonar should block the merge. Even turning compiler warnings to errors in pom.xml is enough to consider this task to be done. The below is just additional details to see the big picture.
Be aware that I am working on code duplication detection right now, and as a side effect, PMD warnngs are also brought to Sonar.
I do not focus on this though, and have no idea whether PMD, CheckStyle, or any other tool is best suited for static code analysis. And it cannot hurt if we check with multiple tools.

[szirbucz]

szirbucz

[magwas]

And yes, everything Eclipse is showing as a warning should lead toblocking the merge.

[szirbucz]

@magwas For static analysis I vote for PMD. On my last project we used both CheckStyle and PMD, because they are good for different goals.
CheckStyle checks the coding conventions, like indentation, spaces around brackets, naming conventions, length of line, etc...
PMD does real static analysis and discovers code smells, code duplication and possible bugs.