code: public CloseableResource<FileSystemMasterClient> acquireMasterClientResource() {
      return new CloseableResource<FileSystemMasterClient>(mFileSystemMasterClientPool.acquire()) {
        @Override
        public void close() {
          mFileSystemMasterClientPool.release(get());
        }
      };
    }
docs: Acquires a file system master client from the file system master client pool. The resource is
  {@code Closeable}.
  
  @return the acquired file system master client resource