Run example tests during the build 

Change-Id: Ib07011762bd617d6937010ca79e5ecd1f862bfba
prefix in tests: TraitJ -> Xtraitj 

Change-Id: I90754f3328410f1d7075d352e55e05dc9ff873a1
removed generator and Main class

They're not used anyway

Change-Id: Id4067faa24eb1b2f0c834aa01e5e1a6b8c4d883b
prefix in main plugin: TraitJ -> Xtraitj

Change-Id: If3e5974cfc64ab91db16e2162cc0c939ee545ca7
removed custom ImportsConfiguration

now that https://bugs.eclipse.org/bugs/show_bug.cgi?id=407390 has been
fixed

Change-Id: I66613b120637df259d517b8932739286fca92c8c
removed unused isRequired method

Change-Id: I35884f7d59b316af719cb33f5a1bbaa5c98142f6