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