code: public CloseableResource<BlockMasterClient> acquireBlockMasterClientResource() {
      return new CloseableResource<BlockMasterClient>(mBlockMasterClientPool.acquire()) {
        @Override
        public void close() {
          mBlockMasterClientPool.release(get());
        }
      };
    }
docs: Acquires a block master client resource from the block master client pool. The resource is
  {@code Closeable}.
  
  @return the acquired block master client resource