code: int toNewByteArray(byte[] dst)
      {
          int length = myBuffer.length - myOffset;
          System.arraycopy(myBuffer, myOffset, dst, 0, length);
          return length;
      }
docs: Copies the current contents of the Ion binary-encoded byte array into a
  a given byte array.
  <p>
  The given array must be large enough to contain all the bytes of the
  Ion binary-encoded byte array.
  <p>
  This makes an unchecked assumption that {{@link #serialize(IonDatagram)}
  is already called.
  <p>
  TODO To be deprecated along with {@link IonDatagram#getBytes(byte[])}
  
  @param dst the byte array into which bytes are to be written
  
  @return the number of bytes copied into {@code dst}