public Service getService(String sentinelName) {
        return services.get(sentinelName);
    }
Returns the service with the given "sentinel name" on this Host,
or null if the name does not match any service.

@param sentinelName the sentinel name of the service we want to return
@return the service with the given sentinel name
config-model/src/main/java/com/yahoo/vespa/model/HostResource.java