'Check and update the object with conditional request
:rtype: Boolean value indicating whether the object is changed'

def update(self):

    conditionalRequestHeader = dict()
    if (self.etag is not None):
        conditionalRequestHeader[Consts.REQ_IF_NONE_MATCH] = self.etag
    if (self.last_modified is not None):
        conditionalRequestHeader[Consts.REQ_IF_MODIFIED_SINCE] = self.last_modified
    (status, responseHeaders, output) = self._requester.requestJson('GET', self._url.value, headers=conditionalRequestHeader)
    if (status == 304):
        return False
    else:
        (headers, data) = self._requester._Requester__check(status, responseHeaders, output)
        self._storeAndUseAttributes(headers, data)
        self.__completed = True
        return True
