title: Maven projects needs to be built to compile?
body: <p>At work I have encountered a couple of projects that in order to compile, it was needed to <code>mvn clean install</code> before. From the architectural point of view, why would it be planned to be like that? Shouldn't the code be independent from the runtime generated code before the deployment? 
  I am missing something here.. 
  If it is contemplated such a thing, do you have any example of a real case that it may be useful?(mixing compilation time code and runtime code)</p>