[PWGJE] Fix: make doRhoAreaSub take const reference to avoid unnecesary copy (#11618)

Author: alcaliva

PWGJE/Core/JetBkgSubUtils.cxx

@@ -160,7 +160,7 @@ std::tuple<double, double> JetBkgSubUtils::estimateRhoPerpCone(const std::vector
   return std::make_tuple(perpPtDensity, perpMdDensity);
 }
 
-fastjet::PseudoJet JetBkgSubUtils::doRhoAreaSub(fastjet::PseudoJet& jet, double rhoParam, double rhoMParam)
+fastjet::PseudoJet JetBkgSubUtils::doRhoAreaSub(const fastjet::PseudoJet& jet, double rhoParam, double rhoMParam)
 {
 
   fastjet::Subtractor sub = fastjet::Subtractor(rhoParam, rhoMParam);

PWGJE/Core/JetBkgSubUtils.h

@@ -79,7 +79,7 @@ class JetBkgSubUtils
   /// @param rhoParam the underlying evvent density vs pT (to be set)
   /// @param rhoParam the underlying evvent density vs jet mass (to be set)
   /// @return jet, background subtracted jet
-  fastjet::PseudoJet doRhoAreaSub(fastjet::PseudoJet& jet, double rhoParam, double rhoMParam);
+  fastjet::PseudoJet doRhoAreaSub(const fastjet::PseudoJet& jet, double rhoParam, double rhoMParam);
 
   /// @brief method that subtracts the background from the input particles using the event-wise cosntituent subtractor
   /// @param inputParticles (all the tracks/clusters/particles in the event)