private int allocatePort() throws InterruptedException {
        int port = PortRangeAllocator.findAvailablePort();
        allocatedPorts.add(port);
        return port;
    }
Tester for running rpc server.

@author Ulf Lilleengen
configserver/src/test/java/com/yahoo/vespa/config/server/rpc/RpcTester.java