diff --git a/externals/kyuubi-flink-sql-engine/src/main/java/org/apache/kyuubi/engine/flink/result/ResultSetUtil.java b/externals/kyuubi-flink-sql-engine/src/main/java/org/apache/kyuubi/engine/flink/result/ResultSetUtil.java
deleted file mode 100644
index 1e709ed64b6..00000000000
--- a/externals/kyuubi-flink-sql-engine/src/main/java/org/apache/kyuubi/engine/flink/result/ResultSetUtil.java
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.apache.kyuubi.engine.flink.result;
-
-import java.util.List;
-import org.apache.flink.table.api.DataTypes;
-import org.apache.flink.table.api.ResultKind;
-import org.apache.flink.table.catalog.Column;
-import org.apache.flink.types.Row;
-
-/** Utility class for flink result sets. */
-public class ResultSetUtil {
-
-  public static ResultSet stringListToResultSet(List<String> strings, String columnName) {
-    Row[] rows = strings.stream().map(Row::of).toArray(Row[]::new);
-    return ResultSet.builder()
-        .resultKind(ResultKind.SUCCESS_WITH_CONTENT)
-        .columns(Column.physical(columnName, DataTypes.STRING()))
-        .data(rows)
-        .build();
-  }
-
-  /**
-   * Build a simple result with OK message. Returned when SQL commands are executed successfully.
-   * Noted that a new ResultSet is returned each time, because ResultSet is stateful (with its
-   * cursor).
-   *
-   * @return A simple result with OK message.
-   */
-  public static ResultSet successResultSet() {
-    return ResultSet.builder()
-        .resultKind(ResultKind.SUCCESS_WITH_CONTENT)
-        .columns(Column.physical("result", DataTypes.STRING()))
-        .data(new Row[] {Row.of("OK")})
-        .build();
-  }
-}
diff --git a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/ExecuteStatement.scala b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/ExecuteStatement.scala
index 0737b87093b..b38ceefa8cc 100644
--- a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/ExecuteStatement.scala
+++ b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/ExecuteStatement.scala
@@ -198,7 +198,7 @@ class ExecuteStatement(
       // reset all properties
       executor.resetSessionProperties(sessionId)
     }
-    resultSet = ResultSetUtil.successResultSet()
+    resultSet = ResultSetUtil.successResultSet
     setState(OperationState.FINISHED)
   }
 
diff --git a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetCatalogs.scala b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetCatalogs.scala
index 4a2506157aa..119a903f253 100644
--- a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetCatalogs.scala
+++ b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetCatalogs.scala
@@ -30,7 +30,7 @@ class GetCatalogs(session: Session)
   override protected def runInternal(): Unit = {
     try {
       val tableEnv = sessionContext.getExecutionContext.getTableEnvironment
-      val catalogs = tableEnv.listCatalogs.toList.asJava
+      val catalogs = tableEnv.listCatalogs.toList
       resultSet = ResultSetUtil.stringListToResultSet(catalogs, TABLE_CAT)
     } catch onError()
   }
diff --git a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTableTypes.scala b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTableTypes.scala
index 56247de93ba..19fd8b3578a 100644
--- a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTableTypes.scala
+++ b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTableTypes.scala
@@ -28,7 +28,7 @@ class GetTableTypes(session: Session)
   extends FlinkOperation(OperationType.GET_TABLE_TYPES, session) {
 
   override protected def runInternal(): Unit = {
-    val tableTypes = Constants.SUPPORTED_TABLE_TYPES.toList.asJava
+    val tableTypes = Constants.SUPPORTED_TABLE_TYPES.toList
     resultSet = ResultSetUtil.stringListToResultSet(tableTypes, TABLE_TYPE)
   }
 }
diff --git a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTables.scala b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTables.scala
index 2d161ba16bb..250a3c0dad0 100644
--- a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTables.scala
+++ b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/operation/GetTables.scala
@@ -65,7 +65,7 @@ class GetTables(
           }
       }
 
-      resultSet = ResultSetUtil.stringListToResultSet(tables.asJava, Constants.SHOW_TABLES_RESULT)
+      resultSet = ResultSetUtil.stringListToResultSet(tables.toList, Constants.SHOW_TABLES_RESULT)
     } catch onError()
   }
 }
diff --git a/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/result/ResultSetUtil.scala b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/result/ResultSetUtil.scala
new file mode 100644
index 00000000000..9fd3118336f
--- /dev/null
+++ b/externals/kyuubi-flink-sql-engine/src/main/scala/org/apache/kyuubi/engine/flink/result/ResultSetUtil.scala
@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.kyuubi.engine.flink.result;
+
+import org.apache.flink.table.api.DataTypes
+import org.apache.flink.table.api.ResultKind
+import org.apache.flink.table.catalog.Column
+import org.apache.flink.types.Row
+
+/** Util for flink result sets. */
+object ResultSetUtil {
+
+  def stringListToResultSet(strings: List[String], columnName: String): ResultSet = {
+    val rows: Array[Row] = strings.map(s => Row.of(s)).toArray(Array[Row](0))
+    ResultSet.builder.resultKind(ResultKind.SUCCESS_WITH_CONTENT).columns(Column.physical(
+      columnName,
+      DataTypes.STRING)).data(rows).build
+  }
+
+  /**
+   * Build a simple result with OK message. Returned when SQL commands are executed successfully.
+   * Noted that a new ResultSet is returned each time, because ResultSet is stateful (with its
+   * cursor).
+   *
+   * @return A simple result with OK message.
+   */
+  def successResultSet: ResultSet =
+    ResultSet.builder.resultKind(ResultKind.SUCCESS_WITH_CONTENT).columns(Column.physical(
+      "result",
+      DataTypes.STRING)).data(Array[Row](Row.of("OK"))).build
+}