[Bug fix] Add a format validation step before format conversion. (#36404)

This PR aims to fix the bug #35225 by introducing a new method IsJson to determine if a given text is in JSON format.
The IsJson method is then utilized in the ToJsonFromXmlOrCsvAsync method to optimize the processing logic.
If the text is already in JSON format, it is returned directly without further conversion from XML or CSV.

Co-authored-by: Heiko <61519853+htcfreek@users.noreply.github.com>

---------

Signed-off-by: Shawn Yuan <shuai.yuan.zju@gmail.com>
Co-authored-by: Heiko <61519853+htcfreek@users.noreply.github.com>

src/modules/AdvancedPaste/AdvancedPaste/Helpers/JsonHelper.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text.Json;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using System.Xml;
@@ -33,6 +34,19 @@ namespace AdvancedPaste.Helpers
         private static readonly Regex CsvRemoveStartAndEndQuotationMarksRegex = new Regex(@"^""(?=(""{2})+)|(?<=(""{2})+)""$");
         private static readonly Regex CsvReplaceDoubleQuotationMarksRegex = new Regex(@"""{2}");
 
+        private static bool IsJson(string text)
+        {
+            try
+            {
+                _ = JsonDocument.Parse(text);
+                return true;
+            }
+            catch (Exception)
+            {
+                return false;
+            }
+        }
+
         internal static async Task<string> ToJsonFromXmlOrCsvAsync(DataPackageView clipboardData)
         {
             Logger.LogTrace();
@@ -46,6 +60,12 @@ namespace AdvancedPaste.Helpers
             var text = await clipboardData.GetTextAsync();
             string jsonText = string.Empty;
 
+            // If the text is already JSON, return it
+            if (IsJson(text))
+            {
+                return text;
+            }
+
             // Try convert XML
             try
             {