private String resolveContentType(URI requestUri) {
        if (resolvePath(requestUri).equals(HISTOGRAMS_PATH)) {
            return "text/plain; charset=utf-8";
        } else if (isPrometheusRequest(requestUri.getQuery())) {
            return "text/plain; version=0.0.4";
        } else {
            return "application/json";
        }
    }
A handler which returns state (health) information from this container instance: Status, metrics and vespa version.

@author Simon Thoresen Hult
container-core/src/main/java/com/yahoo/container/jdisc/state/StateHandler.java