!340 使用instanceof模式匹配, 减少二次转换

Merge pull request !340 from JackyTang/5.X

ruoyi-common/ruoyi-common-mybatis/src/main/java/org/dromara/common/mybatis/interceptor/PlusDataPermissionInterceptor.java

@@ -66,8 +66,8 @@ public class PlusDataPermissionInterceptor extends JsqlParserSupport implements
     @Override
     protected void processSelect(Select select, int index, String sql, Object obj) {
         SelectBody selectBody = select.getSelectBody();
-        if (selectBody instanceof PlainSelect) {
-            this.setWhere((PlainSelect) selectBody, (String) obj);
+        if (selectBody instanceof PlainSelect plainSelect) {
+            this.setWhere(plainSelect, (String) obj);
         } else if (selectBody instanceof SetOperationList setOperationList) {
             List<SelectBody> selectBodyList = setOperationList.getSelects();
             selectBodyList.forEach(s -> this.setWhere((PlainSelect) s, (String) obj));