https://github.com/apache/dubbo/blob/532ce72f8377abf8ff659430b86e0919c9aff562/dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/ServiceConfig.java#L240-L248 

What ever user use `instance` service discovery or `interface` service discovery, we also publish service name mapping info. 
But service name mapping need metadata report dependency, so if some one just use `interface` service discovery, the user still need need metadata report dependency.

Here we add a judgement, check current service config use `instance` service discovery or not, to judge publish service name mapping or not.

try {
                Integer intPort = Integer.parseInt(configPort);
                if (isInvalidPort(intPort)) {
                    throw new IllegalArgumentException("Specified invalid port from env value:" + configPort);
                }
                port = intPort;
            } catch (Exception e) {
                throw new IllegalArgumentException("Specified invalid port from env value:" + configPort);
            }
        }
        return port;
    }
    private String getValueFromConfig(ProtocolConfig protocolConfig, String key) {
        String protocolPrefix = protocolConfig.getName().toUpperCase() + "_";
        String value = ConfigUtils.getSystemProperty(protocolPrefix + key);
        if (StringUtils.isEmpty(value)) {
            value = ConfigUtils.getSystemProperty(key);
        }
        return value;
    }
    private Integer getRandomPort(String protocol) {
        protocol = protocol.toLowerCase();
        return RANDOM_PORT_MAP.getOrDefault(protocol, Integer.MIN_VALUE);
    }
    private void putRandomPort(String protocol, Integer port) {
        protocol = protocol.toLowerCase();
        if (!RANDOM_PORT_MAP.containsKey(protocol)) {
            RANDOM_PORT_MAP.put(protocol, port);
            logger.warn("Use random available port(" + port + ") for protocol " + protocol);
        }