When setting useProxyServer to enable we need to supply

            proxyServerPool value as well

def update(self, **kwargs):
        """When setting useProxyServer to enable we need to supply

            proxyServerPool value as well
        """
        if 'useProxyServer' in kwargs and kwargs['useProxyServer'] == 'enabled':
            if 'proxyServerPool' not in kwargs:
                error = 'Missing proxyServerPool parameter value.'
                raise MissingUpdateParameter(error)
        if hasattr(self, 'useProxyServer'):
            if getattr(self, 'useProxyServer') == 'enabled' and 'proxyServerPool' not in self.__dict__:
                error = 'Missing proxyServerPool parameter value.'
                raise MissingUpdateParameter(error)

        self._update(**kwargs)

        return self