code: @VisibleForTesting
    MemoryPooledByteBuffer newByteBuf(
        InputStream inputStream, MemoryPooledByteBufferOutputStream outputStream) throws IOException {
      mPooledByteStreams.copy(inputStream, outputStream);
      return outputStream.toByteBuffer();
    }
docs: Reads all bytes from inputStream and writes them to outputStream. When all bytes are read
  outputStream.toByteBuffer is called and obtained MemoryPooledByteBuffer is returned
  
  @param inputStream the input stream to read from
  @param outputStream output stream used to transform content of input stream to
  MemoryPooledByteBuffer
  @return an instance of MemoryPooledByteBuffer
  @throws IOException