Add JsonHelper to eliminate duplicated JSON serialization options

Co-authored-by: mdellison90-stack <230609064+mdellison90-stack@users.noreply.github.com>

Author: Copilot

src/shared/Atlassian.Bitbucket.Tests/BitbucketTokenEndpointResponseJsonTest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Text.Json;
+using GitCredentialManager;
 using Xunit;
 
 namespace Atlassian.Bitbucket.Tests
@@ -17,11 +18,7 @@ public void BitbucketTokenEndpointResponseJson_Deserialize_Uses_Scopes()
 
             var json = $"{{\"access_token\": \"{accessToken}\", \"token_type\": \"{tokenType}\", \"expires_in\": {expiresIn}, \"scopes\": \"{scopesString}\", \"scope\": \"{scopeString}\"}}";
 
-            var result = JsonSerializer.Deserialize<BitbucketTokenEndpointResponseJson>(json,
-                new JsonSerializerOptions
-                {
-                    PropertyNameCaseInsensitive = true
-                });
+            var result = JsonSerializer.Deserialize<BitbucketTokenEndpointResponseJson>(json, JsonHelper.CaseInsensitiveOptions);
 
             Assert.Equal(accessToken, result.AccessToken);
             Assert.Equal(tokenType, result.TokenType);

src/shared/Atlassian.Bitbucket.Tests/Cloud/UserInfoTest.cs

@@ -3,6 +3,7 @@
 using System.Text.Json.Serialization;
 using System.Threading.Tasks;
 using Atlassian.Bitbucket.Cloud;
+using GitCredentialManager;
 using Xunit;
 
 namespace Atlassian.Bitbucket.Tests.Cloud
@@ -29,10 +30,7 @@ public void Deserialize_UserInfo()
 
             var json = $"{{\"uuid\": \"{uuid}\", \"has_2fa_enabled\": null, \"username\": \"{userName}\", \"account_id\": \"{accountId}\"}}";
 
-            var result = JsonSerializer.Deserialize<UserInfo>(json, new JsonSerializerOptions()
-            {
-                PropertyNameCaseInsensitive = true,
-            });
+            var result = JsonSerializer.Deserialize<UserInfo>(json, JsonHelper.CaseInsensitiveOptions);
 
             Assert.Equal(userName, result.UserName);
         }

src/shared/Atlassian.Bitbucket/Cloud/BitbucketRestApi.cs

@@ -43,11 +43,7 @@ public async Task<RestApiResult<IUserInfo>> GetUserInformationAsync(string userN
 
                     if (response.IsSuccessStatusCode)
                     {
-                        var obj = JsonSerializer.Deserialize<UserInfo>(json,
-                            new JsonSerializerOptions
-                            {
-                                PropertyNameCaseInsensitive = true,
-                            });
+                        var obj = JsonSerializer.Deserialize<UserInfo>(json, JsonHelper.CaseInsensitiveOptions);
 
                         return new RestApiResult<IUserInfo>(response.StatusCode, obj);
                     }

src/shared/Atlassian.Bitbucket/DataCenter/BitbucketRestApi.cs

@@ -107,12 +107,7 @@ public async Task<List<AuthenticationMethod>> GetAuthenticationMethodsAsync()
 
                     if (response.IsSuccessStatusCode)
                     {
-                        var loginOptions = JsonSerializer.Deserialize<LoginOptions>(json,
-                            new JsonSerializerOptions
-                            {
-                                PropertyNameCaseInsensitive = true,
-                                DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
-                            });
+                        var loginOptions = JsonSerializer.Deserialize<LoginOptions>(json, JsonHelper.CaseInsensitiveIgnoreNullOptions);
 
                         if (loginOptions.Results.Any(r => "LOGIN_FORM".Equals(r.Type)))
                         {

src/shared/Core.Tests/TokenEndpointResponseJsonTest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Text.Json;
+using GitCredentialManager;
 using GitCredentialManager.Authentication.OAuth.Json;
 using Xunit;
 
@@ -17,11 +18,7 @@ public void TokenEndpointResponseJson_Deserialize_Uses_Scope()
         var scopeString = "a,b,c";
         var json = $"{{\"access_token\": \"{accessToken}\", \"token_type\": \"{tokenType}\", \"expires_in\": {expiresIn}, \"scopes\": \"{scopesString}\", \"scope\": \"{scopeString}\"}}";
 
-        var result = JsonSerializer.Deserialize<TokenEndpointResponseJson>(json,
-            new JsonSerializerOptions
-            {
-                PropertyNameCaseInsensitive = true
-            });
+        var result = JsonSerializer.Deserialize<TokenEndpointResponseJson>(json, JsonHelper.CaseInsensitiveOptions);
 
         Assert.Equal(accessToken, result.AccessToken);
         Assert.Equal(tokenType, result.TokenType);

src/shared/Core/Authentication/OAuth/OAuth2Client.cs

@@ -321,10 +321,7 @@ public async Task<OAuth2TokenResult> GetTokenByDeviceCodeAsync(OAuth2DeviceCodeR
                             return result;
                         }
 
-                        var error = JsonSerializer.Deserialize<ErrorResponseJson>(json, new JsonSerializerOptions
-                        {
-                            PropertyNameCaseInsensitive = true
-                        });
+                        var error = JsonSerializer.Deserialize<ErrorResponseJson>(json, JsonHelper.CaseInsensitiveOptions);
 
                         switch (error.Error)
                         {

src/shared/Core/JsonHelper.cs

@@ -0,0 +1,29 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace GitCredentialManager
+{
+    /// <summary>
+    /// Helper class providing common JSON serialization options and utilities.
+    /// </summary>
+    public static class JsonHelper
+    {
+        /// <summary>
+        /// Gets JSON serializer options configured for case-insensitive property names.
+        /// </summary>
+        public static JsonSerializerOptions CaseInsensitiveOptions { get; } = new JsonSerializerOptions
+        {
+            PropertyNameCaseInsensitive = true
+        };
+
+        /// <summary>
+        /// Gets JSON serializer options configured for case-insensitive property names
+        /// and ignoring null values when writing.
+        /// </summary>
+        public static JsonSerializerOptions CaseInsensitiveIgnoreNullOptions { get; } = new JsonSerializerOptions
+        {
+            PropertyNameCaseInsensitive = true,
+            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
+        };
+    }
+}