private InstanceEntity buildInstanceRegisterDTO(final int port) {
        String host = IpUtils.isCompleteHost(this.host) ? this.host : IpUtils.getHost(this.host);
        return InstanceEntity.builder()
                .appName(appName)
                .host(host)
                .port(port)
                .build();
    }
Instantiates a new Instance register listener.

@param config the config
shenyu-spring-boot-starter/shenyu-spring-boot-starter-registry/src/main/java/org/apache/shenyu/springboot/starter/registry/RegistryListener.java