Sends JSON string to Solr instance

def _send_solr_command(self, core_url, json_command):
        """
        Sends JSON string to Solr instance
        """

        # Check document language and dispatch to correct core
        url = _get_url(core_url, "update")
        try:
            response = self.req_session.post(url, data=json_command, headers={'Content-Type': 'application/json'})
            response.raise_for_status()
        except requests.RequestException as e:
            logger.error("Failed to send update to Solr endpoint [%s]: %s", core_url, e, exc_info=True)
            raise SolrException("Failed to send command to Solr [%s]: %s" % (core_url, e,))
        return True