Nacos Client Initialization

  public final static String ENDPOINT = "endpoint";
  public final static String NAMESPACE = "namespace";
  public final static String ACCESS_KEY = "accessKey";
  public final static String SECRET_KEY = "secretKey";
  public final static String SERVER_ADDR = "serverAddr";
  public final static String CONTEXT_PATH = "contextPath";
  public final static String CLUSTER_NAME = "clusterName";
  public final static String ENCODE = "encode";

I. The client can be initialized in either of the following two ways. Choose one; it is required.

Pass Nacos Server information directly, such as ip:port or a domain name.

SERVER_ADDR server address, in the format "ip1:port,ip2:port"
Use an endpoint to access and obtain environment information.
```
ENDPOINT endpoint
CLUSTER_NAME cluster name
```

II. Server path for the connection (optional)

CONTEXT_PATH server root path (default value: nacos)

III. Namespace isolation (optional)

NAMESPACE namespace

IV. Authentication parameters (optional)

ACCESS_KEY public key
SECRET_KEY private key