Add AcceptionPredicateExtension for saving connector resources

Add: AcceptionPredicateExtension mediator prevents all events which the receiver bridge does hot have any handlers for from being sent. That removes a lot of load from bridge connectors if many events are sent but not received.
Remove code duplication from EventBase and EventPredicateBase

Fix: Extracted duplicated of code from EventBase and EventPredicateBase into the package-protected superclass DataObjectBase.