TP validation seems to miss some error cases

Using commit e7d0d56a481a239f3873f688da2dac14dafc2f15 of JBoss Tools target-platforms, it seems like we get in an unperfect state where some dependencies are missing and TP validation misses it. Cf JBIDE-16910 for details about failure that can happen with this commit.

So TP validation needs to be fixed to spot such issues.