Respond to API obsoletion

Author: davidwengier

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Extensions/ProjectExtensions.cs

@@ -14,6 +14,7 @@
 using Microsoft.CodeAnalysis.ExternalAccess.Razor;
 using Microsoft.CodeAnalysis.Razor;
 using Microsoft.CodeAnalysis.Razor.Telemetry;
+using Microsoft.NET.Sdk.Razor.SourceGenerators;
 
 namespace Microsoft.CodeAnalysis;
 
@@ -114,7 +115,16 @@ public static bool TryGetHintNameFromGeneratedDocumentUri(this Project project,
             return false;
         }
 
-        hintName = RazorUri.GetHintNameFromGeneratedDocumentUri(project.Solution, generatedDocumentUri);
+        var identity = RazorUri.GetIdentityOfGeneratedDocument(project.Solution, generatedDocumentUri);
+
+        if (identity.GeneratorTypeName != typeof(RazorSourceGenerator).FullName)
+        {
+            // This is not a Razor source generated document, so we don't know the hint name.
+            hintName = null;
+            return false;
+        }
+
+        hintName = identity.HintName;
         return true;
     }
 }