docs: private void copyToStrBuffer(byte[] buffer, int offset, int length) {
      Preconditions.checkArgument(length >= 0);
      if (strBuffer.length - strBufferIndex < length) {
        // cannot fit, expanding buffer
        expandStrBuffer(length);
      }
      System.arraycopy(
        buffer, offset, strBuffer, strBufferIndex, Math.min(length, MAX_ALLOWABLE_BUFFER_SIZE - strBufferIndex));
      strBufferIndex += length;
    }