Merge branch 'cherry-pick-5c99a242-22.0-mc20' into '22.0-mc20'

Sweeping !46581 from master to 22.0-mc20.
GeneratorObjectsTPCnv: Clear flow information when reading.

See merge request !46611

Generators/GeneratorObjectsTPCnv/src/McEventCollectionCnv_p2.cxx

@@ -288,6 +288,7 @@ McEventCollectionCnv_p2::createGenParticle( const GenParticle_p2& persPart,
 
   // fillin' the flow
   const unsigned int nFlow = persPart.m_flow.size();
+  p->m_flow.clear();
   for ( unsigned int iFlow= 0; iFlow != nFlow; ++iFlow ) {
     p->m_flow.set_icode( persPart.m_flow[iFlow].first,
                          persPart.m_flow[iFlow].second );

Generators/GeneratorObjectsTPCnv/src/McEventCollectionCnv_p3.cxx

@@ -315,6 +315,7 @@ McEventCollectionCnv_p3::createGenParticle( const GenParticle_p3& persPart,
 
   // setup flow
   const unsigned int nFlow = persPart.m_flow.size();
+  p->m_flow.clear();
   for ( unsigned int iFlow= 0; iFlow != nFlow; ++iFlow ) {
     p->m_flow.set_icode( persPart.m_flow[iFlow].first,
                          persPart.m_flow[iFlow].second );

Generators/GeneratorObjectsTPCnv/src/McEventCollectionCnv_p4.cxx

@@ -537,6 +537,7 @@ McEventCollectionCnv_p4::createGenParticle( const GenParticle_p4& persPart,
 
   // setup flow
   const unsigned int nFlow = persPart.m_flow.size();
+  p->m_flow.clear();
   for ( unsigned int iFlow= 0; iFlow != nFlow; ++iFlow )
     {
       p->m_flow.set_icode( persPart.m_flow[iFlow].first,