code: public static final void getByteArray(byte[] data, int offset, int size, byte[] buffer, int bufferOffset)
     {
        System.arraycopy(data, offset, buffer, bufferOffset, size);
     }
docs: This method extracts a portion of a byte array and writes it into
  another byte array.
  
  @param data Source data
  @param offset Offset into source data
  @param size Required size to be extracted from the source data
  @param buffer Destination buffer
  @param bufferOffset Offset into destination buffer