When updating from 4.2.0 to 4.2.1, a user might decide to only update Central or Project Examples, and NOT update Foundation.core, which means his Eclipse will still think it's 4.2.0, not 4.2.1, and he might get the wrong version of central/examples.

Therefore we need manifest-level [4.2.1,) requirements on upstream foundation.core in examples and central, to force this lock-step updating.

And we need to use the maven enforcer plugin to fail the build if these versions get out of sync.