[FLINK-37924][table] Improve comments and formatting code

Author: JinkunLiu

flink-table/flink-sql-parser/src/main/java/org/apache/calcite/sql/fun/SqlItemOperator.java

@@ -14,6 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.apache.calcite.sql.fun;
 
 import org.apache.calcite.rel.type.RelDataType;
@@ -49,7 +50,7 @@
  * <p>This class was copied over from Calcite 1.39.0 version to support access variant
  * (FLINK-37924).
  *
- * <p>Line 148, CALCITE-7325, should be removed after upgrading Calcite to 1.42.0.
+ * <p>Line 148 ~ 153, CALCITE-7325, should be removed after upgrading Calcite to 1.42.0.
  */
 public class SqlItemOperator extends SqlSpecialOperator {
     public final int offset;
@@ -144,10 +145,12 @@ private static SqlSingleOperandTypeChecker getChecker(SqlCallBinding callBinding
     @Override
     public String getAllowedSignatures(String name) {
         if (name.equals("ITEM")) {
+            // FLINK MODIFICATION BEGIN
             return "<ARRAY>[<INTEGER>]\n"
                     + "<MAP>[<ANY>]\n"
                     + "<ROW>[<CHARACTER>|<INTEGER>]\n"
                     + "<VARIANT>[<CHARACTER>|<INTEGER>]";
+            // FLINK MODIFICATION END
         } else {
             return "<ARRAY>[" + name + "(<INTEGER>)]";
         }

flink-table/flink-table-common/src/main/java/org/apache/flink/table/types/inference/strategies/ItemAtIndexArgumentTypeStrategy.java

@@ -43,8 +43,8 @@
  * <p>the type to be equal to the key type of {@link LogicalTypeRoot#MAP} if the first argument is a
  * map
  *
- * <p>a {@link LogicalTypeFamily#NUMERIC} type or {LogicalTypeFamily.CHARACTER_STRING} type if the
- * first argument is a {@link LogicalTypeRoot#VARIANT}.
+ * <p>a {@link LogicalTypeFamily#NUMERIC} type or {@link LogicalTypeFamily#CHARACTER_STRING} type if
+ * the first argument is a {@link LogicalTypeRoot#VARIANT}.
  */
 @Internal
 public final class ItemAtIndexArgumentTypeStrategy implements ArgumentTypeStrategy {

flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/planner/codegen/CodeGenUtils.scala

@@ -43,7 +43,7 @@ import org.apache.flink.table.types.logical.utils.LogicalTypeUtils.toInternalCon
 import org.apache.flink.table.types.utils.DataTypeUtils.isInternal
 import org.apache.flink.table.utils.EncodingUtils
 import org.apache.flink.types.{ColumnList, Row, RowKind}
-import org.apache.flink.types.variant.{BinaryVariant, Variant}
+import org.apache.flink.types.variant.Variant
 
 import java.lang.{Boolean => JBoolean, Byte => JByte, Double => JDouble, Float => JFloat, Integer => JInt, Long => JLong, Object => JObject, Short => JShort}
 import java.lang.reflect.Method

flink-table/flink-table-planner/src/test/java/org/apache/flink/table/planner/plan/nodes/exec/stream/VariantSemanticTest.java

@@ -37,7 +37,6 @@
 import static org.apache.flink.table.api.Expressions.$;
 
 /** Semantic tests for {@link DataTypes#VARIANT()} type. */
-@SuppressWarnings("checkstyle:LocalFinalVariableName")
 public class VariantSemanticTest extends SemanticTestBase {
 
     static final VariantBuilder BUILDER = Variant.newBuilder();