public ConfigResponse resolveConfig(JRTServerConfigRequest request, GetConfigContext context, Optional<Version> vespaVersion) {
        context.trace().trace(TRACELEVEL, "RpcServer.resolveConfig()");
        return context.requestHandler().resolveConfig(context.applicationId(), request, vespaVersion);
    }
Returns the tenant for this request, empty if there is none
(which on hosted Vespa means that the requesting host is not currently active for any tenant)
configserver/src/main/java/com/yahoo/vespa/config/server/rpc/RpcServer.java