HepMC::GenEventBarcodes Node1 HepMC::GenEventBarcodes   + from_string() + to_string() + barcode_to_vertex() + barcode_to_vertex() + barcode_to_particle() + barcode_to_particle() + add() + remove() + add() + remove() + barcode_to_vertex_map() + barcode_to_particle _map() + id_to_barcode_map() + fillAttribute() Node2 HepMC3::Attribute     Node2->Node1 Node3 std::unordered_map < int, GenVertexPtr > + keys + elements   Node3->Node1 -m_vertexBC Node4 std::unordered_map < int, GenParticlePtr > + keys + elements   Node4->Node1 -m_particleBC