code: public boolean unlockBlock(long sessionId, long blockId) {
      synchronized (mSharedMapsLock) {
        Set<Long> sessionLockIds = mSessionIdToLockIdsMap.get(sessionId);
        if (sessionLockIds == null) {
          return false;
        }
        for (long lockId : sessionLockIds) {
          LockRecord record = mLockIdToRecordMap.get(lockId);
          if (record == null) {
            // TODO(peis): Should this be a check failure?
            return false;
          }
          if (blockId == record.getBlockId()) {
            mLockIdToRecordMap.remove(lockId);
            sessionLockIds.remove(lockId);
            if (sessionLockIds.isEmpty()) {
              mSessionIdToLockIdsMap.remove(sessionId);
            }
            Lock lock = record.getLock();
            unlock(lock, blockId);
            return true;
          }
        }
        return false;
      }
    }
docs: TODO(bin): Temporary, remove me later.