fix connectparam and hascollection param databaseName can be null.

Signed-off-by: “yelusion” <xun.huang@zilliz.com>

src/main/java/io/milvus/param/ConnectParam.java

@@ -136,7 +136,7 @@ public class ConnectParam {
          * @param databaseName databaseName
          * @return <code>Builder</code>
          */
-        public Builder withDatabaseName(@NonNull String databaseName) {
+        public Builder withDatabaseName(String databaseName) {
             this.databaseName = databaseName;
             return this;
         }

src/main/java/io/milvus/param/MultiConnectParam.java

@@ -92,7 +92,7 @@ public class MultiConnectParam extends ConnectParam {
          * @param databaseName databaseName
          * @return <code>Builder</code>
          */
-        public Builder withDatabaseName(@NonNull String databaseName) {
+        public Builder withDatabaseName(String databaseName) {
             super.withDatabaseName(databaseName);
             return this;
         }

src/main/java/io/milvus/param/collection/HasCollectionParam.java

@@ -55,12 +55,12 @@ public class HasCollectionParam {
         }
 
         /**
-         * Sets the database name. Database name can be empty.
+         * Sets the database name.
          *
          * @param databaseName database name
          * @return <code>Builder</code>
          */
-        public Builder withDatabaseName(@NonNull String databaseName) {
+        public Builder withDatabaseName(String databaseName) {
             this.databaseName = databaseName;
             return this;
         }