/**
   * Create INVITE request
   *
   * @param content Content part
   * @return Request
   * @throws PayloadException
   */
  private SipRequest createInviteRequest(String content) throws PayloadException {
    try {
      SipRequest invite =
          SipMessageFactory.createMultipartInvite(
              getDialogPath(), getFeatureTags(), getAcceptContactTags(), content, BOUNDARY_TAG);
      if (getSubject() != null) {
        invite.addHeader(SubjectHeader.NAME, getSubject());
      }
      invite.addHeader(RequireHeader.NAME, "recipient-list-invite");
      invite.addHeader(ChatUtils.HEADER_CONTRIBUTION_ID, getContributionID());
      return invite;

    } catch (ParseException e) {
      throw new PayloadException("Failed to create invite request!", e);
    }
  }