private static Optional<ClusterState> clusterStateFromReply(final WrongDistributionReply reply) {
            try {
                return Optional.of(new ClusterState(reply.getSystemState()));
            } catch (Exception e) {
                reply.getTrace().trace(1, "Error when parsing system state string " + reply.getSystemState());
                return Optional.empty();
            }
        }
Message context class. Contains data we want to inspect about a request at reply time.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/ContentPolicy.java