EDM4hep: mcparticles -> MCParticles

benchmarks/track_finding/scripts/rec_multiple_tracks.cxx

@@ -93,7 +93,7 @@ int rec_multiple_tracks(const char* fname = "topside/rec_multiple_tracks.root")
                  .Define("thrownParticles", "MCParticles[isThrown]")
                  .Define("thrownP", fourvec, {"thrownParticles"})
                  .Define("nThrown", "thrownParticles.size()")
-                 .Define("nProto", "outputProtoTracks.size()")
+                 .Define("nProto", "nProtoTracks")
                  .Define("p_thrown", momentum, {"thrownP"})
                  .Define("theta_thrown", theta, {"thrownP"})
                  .Define("theta0", "theta_thrown[0]")