removed some unused imports
removed some unused imports


Former-commit-id: 255f39ad2f7839ef862da4b64ec05e41a018326f [formerly 255f39ad2f7839ef862da4b64ec05e41a018326f [formerly 083c6eb6023f5f847095103b57e413f1e624ec59]]
Former-commit-id: 34526603a718f47513b8f23496d6d6b9bc231be6
Former-commit-id: da623c9502326f197276e0a4084432a614e0990c
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine