Fix member function names in ParticleCombination
Fix some naming problems in ParticleCombination that were detected at runtime in Moore when creating combinations of v2 particle objects.
Related to LHCb!3378 (merged), Moore!1274 (merged)
Fix some naming problems in ParticleCombination that were detected at runtime in Moore when creating combinations of v2 particle objects.
Related to LHCb!3378 (merged), Moore!1274 (merged)