From bc4619b4f2be318f0ba19af0561f19bd8a14cd4d Mon Sep 17 00:00:00 2001
From: Fabio Cossutti <fabio.cossutti@ts.infn.it>
Date: Wed, 17 Mar 2021 11:46:01 +0100
Subject: [PATCH] Fix the order of multiple ETL hits to follow the expected
 convention

---
 RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc b/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc
index 426eb04bce2ae..ea8b21f143d56 100644
--- a/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc
+++ b/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc
@@ -875,6 +875,14 @@ TransientTrackingRecHit::ConstRecHitContainer TrackExtenderWithMTDT<TrackCollect
 
     fillMatchingHits(ilay, tsos, traj, pmag2, pathlength0, hits, prop, bs, vtxTime, matchVertex, output, bestHit);
   }
+
+  // the ETL hits order must be from the innermost to the outermost
+
+  if (output.size() == 2) {
+    if (std::abs(output[0]->globalPosition().z()) > std::abs(output[1]->globalPosition().z())) {
+      std::reverse(output.begin(), output.end());
+    }
+  }
   return output;
 }