Not allow empty username

Signed-off-by: yhmo <yihua.mo@zilliz.com>

Author: yhmo

sdk-core/src/main/java/io/milvus/param/ConnectParam.java

@@ -491,6 +491,9 @@ public Builder withRpcDeadline(long deadline, TimeUnit timeUnit) {
          * @return <code>Builder</code>
          */
         public Builder withAuthorization(String username, String password) {
+            if (username == null || username.trim().isEmpty()) {
+                throw new IllegalArgumentException("Username cannot be null or blank");
+            }
             this.authorization = Base64.getEncoder().encodeToString(String.format("%s:%s", username, password).getBytes(StandardCharsets.UTF_8));
             this.userName = username;
             return this;

sdk-core/src/main/java/io/milvus/v2/client/ConnectConfig.java

@@ -354,6 +354,9 @@ public ConnectConfigBuilder token(String token) {
         }
 
         public ConnectConfigBuilder username(String username) {
+            if (username == null || username.trim().isEmpty()) {
+                throw new IllegalArgumentException("Username cannot be null or blank");
+            }
             this.username = username;
             return this;
         }