code: @Override
      public CallProgressMessage createCPG() {
          CallProgressMessage msg = new CallProgressMessageImpl(_CPG_HOLDER.mandatoryCodes, _CPG_HOLDER.mandatoryVariableCodes,
                  _CPG_HOLDER.optionalCodes, _CPG_HOLDER.mandatoryCodeToIndex, _CPG_HOLDER.mandatoryVariableCodeToIndex,
                  _CPG_HOLDER.optionalCodeToIndex);
          return msg;
      }
docs: /*
  (non-Javadoc)
  
  @see org.restcomm.protocols.ss7.isup.ISUPMessageFactory#createCPG()