NullPointerException for ZookeeperAutoServiceRegistration

[ivan-zaitsev]

ZookeeperAutoServiceRegistration throws an exception when ServiceInstanceRegistration method getServiceInstance() is called before ZookeeperAutoServiceRegistration method getPort()

It happens because method getServiceInstance() calls build() and when getPort() will be called it will return null instead 0.

spring-cloud-zookeeper/spring-cloud-zookeeper-discovery/src/main/java/org/springframework/cloud/zookeeper/serviceregistry/ServiceInstanceRegistration.java

Lines 64 to 69 in ec845a4

	public ServiceInstance<ZookeeperInstance> getServiceInstance() {
	if (this.serviceInstance == null) {
	build();
	}
	return this.serviceInstance;
	}

spring-cloud-zookeeper/spring-cloud-zookeeper-discovery/src/main/java/org/springframework/cloud/zookeeper/serviceregistry/ServiceInstanceRegistration.java

Lines 71 to 73 in ec845a4

	protected void build() {
	this.serviceInstance = this.builder.build();
	}

spring-cloud-zookeeper/spring-cloud-zookeeper-discovery/src/main/java/org/springframework/cloud/zookeeper/serviceregistry/ServiceInstanceRegistration.java

Lines 83 to 88 in ec845a4

	public int getPort() {
	if (this.serviceInstance == null) {
	return 0;
	}
	return this.serviceInstance.getPort();
	}

spring-cloud-zookeeper/spring-cloud-zookeeper-discovery/src/main/java/org/springframework/cloud/zookeeper/serviceregistry/ZookeeperAutoServiceRegistration.java

Lines 70 to 79 in ec845a4

	protected void register() {
	if (!this.properties.isRegister()) {
	log.debug("Registration disabled.");
	return;
	}
	if (this.registration.getPort() == 0) {
	this.registration.setPort(getPort().get());
	}
	super.register();
	}

Also getInstanceId() method returns null.

Use case when we need to call getServiceInstance for example to create leader candidate and associate with registration id for further understanding which node is a leader.

@Bean
public DefaultCandidate bean(ServiceInstanceRegistration registration) {
    return return new DefaultCandidate(registration.getServiceInstance().getId(), "default");
}

[ivan-zaitsev]

As workaround for fixing this: before calling registration.getServiceInstance() this line should be called registration.setPort(0);

For example:

@Bean
public DefaultCandidate bean(ServiceInstanceRegistration registration) {
    registration.setPort(0);
    return return new DefaultCandidate(registration.getServiceInstance().getId(), "default");
}

Not so elegant solution, but it works.