Update to field to fields (#2999)

This pull request introduces improvements to error handling and logging
for image download and field mapping operations in the migration tools.
The most notable changes are enhanced diagnostics for failed image
downloads and field value mappings, and a modification to HTTP client
configuration to allow redirects.

**Error handling and diagnostics improvements:**

* Added detailed logging for failed image downloads in
`TfsEmbededImagesTool.cs`, including HTTP status codes and reason
phrases for non-404 errors.
* Enhanced debugging information in `EmbededImagesRepairEnricherBase.cs`
by logging failed HTTP responses, including status codes, reason
phrases, and location headers.

**Field mapping logic:**

* Updated `FieldToFieldMap.cs` to log when a field mapping is skipped
due to an empty value, providing clearer diagnostics for mapping
operations.

**HTTP client configuration:**

* Changed the HTTP client handler in
`EmbededImagesRepairEnricherBase.cs` to allow automatic redirects,
improving compatibility with redirected image URLs.

Author: MrHinsh

src/MigrationTools.Clients.TfsObjectModel/Tools/FieldMappingTool/FieldMaps/FieldToFieldMap.cs

@@ -66,9 +66,17 @@ internal override void InternalExecute(WorkItem source, WorkItem target)
             value = Config.defaultValue;
         }
 
-        target.Fields[Config.targetField].Value = value;
-        Log.LogDebug("FieldToFieldMap: [UPDATE] Successfully mapped field {SourceField} to {TargetField} with value '{Value}' using mode {FieldMapMode} | Source WorkItem: {SourceId} -> Target WorkItem: {TargetId}", 
-            Config.sourceField, Config.targetField, value, Config.fieldMapMode, source.Id, target.Id);
+        if (!string.IsNullOrEmpty(value))
+        {
+            target.Fields[Config.targetField].Value = value;
+            Log.LogDebug("FieldToFieldMap: [UPDATE] Successfully mapped field {SourceField} to {TargetField} with value '{Value}' using mode {FieldMapMode} | Source WorkItem: {SourceId} -> Target WorkItem: {TargetId}",
+               Config.sourceField, Config.targetField, value, Config.fieldMapMode, source.Id, target.Id);
+        }
+        else
+        {
+            Log.LogDebug("FieldToFieldMap: [SKIPPED] Proposed value is empty {SourceField} to {TargetField} with value '{Value}' using mode {FieldMapMode} | Source WorkItem: {SourceId} -> Target WorkItem: {TargetId}",
+               Config.sourceField, Config.targetField, value, Config.fieldMapMode, source.Id, target.Id);
+        }
     }
 
     private bool IsValid(WorkItem source, WorkItem target)

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsEmbededImagesTool.cs

@@ -150,6 +150,10 @@ private string UploadedAndRetrieveAttachmentLinkUrl(string matchedSourceUri, str
                         }
                         else
                         {
+                            // Provide more detailed error information for non-404 failures
+                            Log.LogWarning("EmbededImagesRepairEnricher: Failed to download image {MatchValue} from WorkItem {WorkItemId}, Field {FieldName}. Status: {StatusCode} ({ReasonPhrase})",
+                                matchedSourceUri, targetWorkItem.Id, sourceFieldName, (int)result.StatusCode, result.ReasonPhrase);
+                            
                             result.EnsureSuccessStatusCode();
                         }
                     }

src/MigrationTools/Tools/Infrastructure/EmbededImagesRepairEnricherBase.cs

@@ -18,7 +18,7 @@ namespace MigrationTools.Tools.Infrastructure
 
         protected EmbededImagesRepairToolBase(IOptions<ToolOptions> options, IServiceProvider services, ILogger<ITool> logger, ITelemetryLogger telemetry) : base(options, services, logger, telemetry)
         {
-            _httpClientHandler = new HttpClientHandler { AllowAutoRedirect = false, UseDefaultCredentials = true, AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate };
+            _httpClientHandler = new HttpClientHandler { AllowAutoRedirect = true, UseDefaultCredentials = true, AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate };
         }
 
         /**
@@ -41,6 +41,13 @@ protected static HttpResponseMessage DownloadFile(HttpClient httpClient, string
                     }
                 }
             }
+            else
+            {
+                // Log details about non-success responses for debugging
+                var logger = Microsoft.Extensions.Logging.LoggerFactory.Create(builder => builder.AddConsole()).CreateLogger("EmbededImagesRepairEnricher");
+                logger.LogDebug("DownloadFile failed for URL {Url}. Status: {StatusCode} ({ReasonPhrase}). Location header: {LocationHeader}",
+                    url, (int)response.StatusCode, response.ReasonPhrase, response.Headers.Location?.ToString() ?? "None");
+            }
 
             return response;
         }
@@ -126,4 +133,4 @@ protected enum ImageFormat
             jpeg
         }
     }
-}
+}