Bug #447339 - Skip Bean Validation on objects that are not constrained.
Bug #328372 - validator used by default
Bug #391566 - perf: validator listener should not be set on entities with no constraints

Signed-off-by: Marcel Valovy <marcel.valovy@oracle.com>
Reviewed-by: Martin Grebac, Lukas Jungmann, Iaroslav Savitskyi, Tomas Kraus, Miroslav Kos
Hot fix: diamond (Java 1.7) made build fail.

Signed-off-by: Marcel Valovy <marcel.valovy@oracle.com>