Made callbacks abstract.
Made callbacks abstract.


Former-commit-id: ce5d4f6e033b2d2f79133c83f232095ccb491eb1 [formerly 80b20fd56499e007efa9559efd574a51ce2ae4ca]
Former-commit-id: 07c14eb50c1d48a3f018be4f44179a14ac01b1f3
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine