fix: extraneous null prop removal

Signed-off-by: Vincent Biret <vibiret@microsoft.com>

src/Microsoft.OpenApi/Models/References/OpenApiParameterReference.cs

@@ -68,7 +68,7 @@ public OpenApiParameterReference(OpenApiParameterReference parameter)
         {
             Utils.CheckArgumentNull(parameter);
             Reference = parameter.Reference != null ? new(parameter.Reference) : null;
-            UnresolvedReference = parameter?.UnresolvedReference ?? false;
+            UnresolvedReference = parameter.UnresolvedReference;
             //no need to copy summary and description as if they are not overridden, they will be fetched from the target
             //if they are, the reference copy will handle it
         }