code: public void put(byte[] source, int index, int length)
      {
          // If the buffer is small.
          if (mBuffer.capacity() < (mLength + length))
          {
              expandBuffer(mLength + length + ADDITIONAL_BUFFER_SIZE);
          }
  
          mBuffer.put(source, index, length);
          mLength += length;
      }
docs: Add data at the current position.
  
  @param source
  Source data.
  
  @param index
  The index in the source data. Data from the index is copied.
  
  @param length
  The length of data to copy.