Meaningless Code？

[Arvinaa]

In com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl method syncUp, why need call method isRegisterable? and how to understand logic of method isRegisterable(Instance instance)? the method code as follow:

/**
     * Checks if an instance is registerable in this region. Instances from other regions are rejected.
     *
     * @param instanceInfo  th instance info information of the instance
     * @return true, if it can be registered in this server, false otherwise.
     */
    public boolean isRegisterable(InstanceInfo instanceInfo) {
        DataCenterInfo datacenterInfo = instanceInfo.getDataCenterInfo();
        String serverRegion = clientConfig.getRegion();
        if (AmazonInfo.class.isInstance(datacenterInfo)) {
            AmazonInfo info = AmazonInfo.class.cast(instanceInfo.getDataCenterInfo());
            String availabilityZone = info.get(MetaDataKey.availabilityZone);
            // Can be null for dev environments in non-AWS data center
            if (availabilityZone == null && US_EAST_1.equalsIgnoreCase(serverRegion)) {
                return true;
            } else if ((availabilityZone != null) && (availabilityZone.contains(serverRegion))) {
                // If in the same region as server, then consider it registerable
                return true;
            }
        }
        return true; // Everything non-amazon is registrable.
    }

[error0702]

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[dgfwork]

this code is used to determine whether a service instance should be registered with the Eureka service registry based on its data center information and the client's configuration. It enforces conditions for registration in AWS environments but defaults to allowing registration in other environments. The practical significance of this code depends on the specific deployment and use cases, and it may appear to have limited usefulness in some situations.