@Override
    public boolean serviceExists(final String key) {
        try {
            return !selectInstances(key).isEmpty();
        } catch (Exception e) {
            throw new ShenyuException(e);
        }
    }
The type Etcd instance register repository.
shenyu-registry/shenyu-registry-etcd/src/main/java/org/apache/shenyu/registry/etcd/EtcdInstanceRegisterRepository.java