Merge nested if statement

Author: MaggieKimani1

src/Microsoft.OpenApi/Reader/V31/OpenApiV31Deserializer.cs

@@ -158,12 +158,9 @@ private static (string, string) GetReferenceIdAndExternalResource(string pointer
 
             var isExternalResource = !refSegments.First().StartsWith("#");
             string externalResource = null;
-            if (isExternalResource)
+            if (isExternalResource && pointer.Contains('#'))
             {
-                if (pointer.Contains('#'))
-                {
-                    externalResource = $"{refSegments.First()}/{refSegments[1].TrimEnd('#')}";
-                }
+                externalResource = $"{refSegments.First()}/{refSegments[1].TrimEnd('#')}";
             }
 
             return (refId, externalResource);