PRD_MultiTruthCollection Node1 PRD_MultiTruthCollection Node2 std::multimap< Identifier, HepMcParticleLink, std ::less< Identifier >, SG ::ArenaPoolSTLAllocator< std::pair< const Identifier, HepMcParticleLink > > > Node2->Node1 Node3 K Node3->Node2 +keys Node4 T Node4->Node2 +elements