Improve MIME type handling in GxHttpClient (#1236)

Added MimeTypesMap v1.0.9 to GxClasses.csproj to provide consistent MIME type resolution in .NET Core.
Added a lightweight MIME helper for .NET Framework to avoid introducing an additional dependency while ensuring correct .json resolution.

Co-authored-by: claudiamurialdo <[email protected]>

Author: claudiamurialdo

dotnet/src/dotnetcore/GxClasses/GxClasses.csproj

@@ -144,6 +144,7 @@
 		<PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
 		<PackageReference Include="Microsoft.Extensions.Logging.ApplicationInsights" Version="2.22.0" PrivateAssets="ALL" />
 		<PackageReference Include="Azure.Monitor.OpenTelemetry.Exporter" Version="1.1.0" PrivateAssets="All" />
+		<PackageReference Include="MimeTypesMap" Version="1.0.9" />
 		<PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.7.0" PrivateAssets="All" />
 		<PackageReference Include="OpenTelemetry.Exporter.Console" Version="1.7.0" PrivateAssets="All" />
 		<PackageReference Include="Pgvector" Version="0.3.0" PrivateAssets="All" />

dotnet/src/dotnetframework/GxClasses/Domain/GxHttpClient.cs

@@ -23,6 +23,7 @@ namespace GeneXus.Http.Client
 	using GeneXus.Utils;
 
 #if NETCORE
+	using HeyRed.Mime;
 	using Microsoft.AspNetCore.WebUtilities;
 #endif
 	using Mime;
@@ -721,7 +722,11 @@ private void StartMultipartFile(string name, string s)
 					name = Path.GetFileNameWithoutExtension(s);
 				}
 				SendStream.Write(MultiPart.Boundarybytes, 0, MultiPart.Boundarybytes.Length);
-				string header = string.Format(MultiPart.HeaderTemplate, name, s, MimeMapping.GetMimeMapping(s));
+#if NETCORE
+				string header = string.Format(MultiPart.HeaderTemplate, name, s, MimeTypesMap.GetMimeType(s));
+#else
+				string header = string.Format(MultiPart.HeaderTemplate, name, s, MimeHelper.GetMimeMapping(s));
+#endif
 				byte[] headerbytes = Encoding.UTF8.GetBytes(header);
 				SendStream.Write(headerbytes, 0, headerbytes.Length);
 			}
@@ -1078,7 +1083,7 @@ async Task ReadResponseDataAsync()
 				}
 			}
 		}
-		#endif
+#endif
 		bool UseOldHttpClient(string name)
 		{
 			if (Config.GetValueOf("useoldhttpclient", out string useOld) && useOld.StartsWith("y", StringComparison.OrdinalIgnoreCase))
@@ -2155,5 +2160,27 @@ public string Password
 		}
 
 	}
+#if !NETCORE
+	internal static class MimeHelper
+	{
+		private static readonly Dictionary<string, string> CustomMap =
+			new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+			{
+			{ ".json", "application/json" },
+			};
+
+		public static string GetMimeMapping(string fileName)
+		{
+			string ext = Path.GetExtension(fileName);
+
+			if (!string.IsNullOrEmpty(ext) &&
+				CustomMap.TryGetValue(ext, out string forcedMime))
+			{
+				return forcedMime;
+			}
+			return MimeMapping.GetMimeMapping(fileName);
+		}
+	}
+#endif
 
 }