Summary: closes https://github.com/facebook/rocksdb/issues/7917 Implemented ByteBuffer API variants of Java keyMayExist() uniformly with and without column families, read options and return data values. Implemented 2 supporting C++ JNI methods. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9013 Reviewed By: mrambacher Differential Revision: D31665989 Pulled By: jay-zhuang fbshipit-source-id: 8adc1730217dba38d6fa7b31d788650a33e28af1