code: @Override
  	public Response cancelReserveRN(String corpNum, String requestNum)
  			throws PopbillException {
  		return cancelReserveRN(corpNum, requestNum, null);
  	}
docs: /*
  (non-Javadoc)
  @see com.popbill.api.FaxService#cancelReserveRN(java.lang.String, java.lang.String)