fix: applying copilot feedback

Author: suhwan-cheon

flink-cdc-connect/flink-cdc-pipeline-connectors/flink-cdc-pipeline-connector-iceberg/src/main/java/org/apache/flink/cdc/connectors/iceberg/sink/IcebergMetadataApplier.java

@@ -252,6 +252,9 @@ private void applyAddColumnEventWithPosition(Table table, AddColumnEvent event)
                     case LAST:
                         break;
                     case BEFORE:
+                        checkNotNull(
+                                columnWithPosition.getExistedColumnName(),
+                                "Existing column name must be provided for BEFORE position");
                         updateSchema.moveBefore(
                                 columnName, columnWithPosition.getExistedColumnName());
                         break;

flink-cdc-connect/flink-cdc-pipeline-connectors/flink-cdc-pipeline-connector-iceberg/src/main/java/org/apache/flink/cdc/connectors/iceberg/sink/utils/IcebergTypeUtils.java

@@ -72,6 +72,7 @@ public static Literal<?> parseDefaultValue(
         if (defaultValueExpression == null) {
             return null;
         }
+        defaultValueExpression = defaultValueExpression.trim();
         try {
             switch (cdcType.getTypeRoot()) {
                 case CHAR:
@@ -104,7 +105,7 @@ public static Literal<?> parseDefaultValue(
                             new java.math.BigDecimal(defaultValueExpression)
                                     .setScale(scale, java.math.RoundingMode.HALF_UP));
                 default:
-                    LOG.warn(
+                    LOG.debug(
                             "Unsupported default value type {} for expression '{}', skipping default value.",
                             cdcType.getTypeRoot(),
                             defaultValueExpression);