MassProcessingPhaseManager owns separateFMassProcessingPhaseinstances for every ETickingGroup. When activated via Start function it registers and enables theFMassProcessingPhaseinstances which themselves are tick functions that hostUMassCompositeProcessorwhich they trigger as part of their Tick function. MassProcessingPhaseManager serves as an interface to saidFMassProcessingPhaseinstances and allows initialization with collections of processors (via Initialize function) as well as registering arbitrary functions to be called when a particular phase starts or ends (via GetOnPhaseStart and GetOnPhaseEnd functions).