Final interface

From APIDesign

Final interface is a pattern often used in vendor library style API design. It marks a Java interface in an API as final (either in Javadoc or elsewhere TBD) with the evolution plan to expand it incompatibly (from the point of implementers). The hope is that nobody except the implementers will every implement such interface.

TBD

Why it does not work?

DOM2 vs. DOM3 problems (TBD): (including the ones provided by the JDK itself) which worked, while one had just one such combo on in own application, but caused linkage problems when JDK continued to distribute DOM2 and there were modern parser and applications trying to use DOM3 (which contains incompatible interfaces from provider point of view).

Why it works?

All of this can be mitigated if one has good runtime support for modularity and this may be the reason why the vendor library seems to be very popular in OSGi world. The API part can request proper implementation and the OSGi container will select the right one. Especially with OSGi4.3 capabilities this seems very easy to specify and achieve.