code: private static void writeMIMEBoundaryClosure(final OutputStreamWriter outWriter, final String boundaryID)
              throws IOException {
          outWriter.write(String.format("--%s--\r\n", boundaryID));
      }
docs: Reserved for internal use. Writes a MIME part boundary closure to the output stream.
  
  @param outWriter
  The {@link OutputStreamWriter} to write the MIME part boundary closure to.
  @param boundaryID
  The <code>String</code> containing the MIME part boundary string.
  @throws IOException
  if an error occurs writing to the output stream.