def set_system_conf(self, key=None, value=None, d=None):
        """ Sets a java system property as a ('key', 'value') pair of using a dictionary
        {'key': 'value', ...}

        :param key: string
        :param value: string
        :param d: dictionary
        :return: None
        """
        if isinstance(d, dict):
            self._system.update(d)
        elif isinstance(key, str) and isinstance(value, str):
            self._system[key] = value
        else:
            raise TypeError("key, value must be strings")
Sets a java system property as a ('key', 'value') pair of using a dictionary
        {'key': 'value', ...}

        :param key: string
        :param value: string
        :param d: dictionary
        :return: None