long spentTime() {
            return System.currentTimeMillis() - startTime;
        }
Rpc server for the metrics proxy.

When a new object is created after reconfiguration, it will claim ownership of the methods
in the given {@link RpcConnector}. This is ok because at the time this component is created,
all components it depends on are already created.

@author gjoranv
metrics-proxy/src/main/java/ai/vespa/metricsproxy/rpc/RpcServer.java