virtual void PrepareSourceItems ( [UNiagaraHierarchyRoot](API\Plugins\NiagaraEditor\ViewModels\HierarchyEditor\UNiagaraHierarchyRoot) * SourceRoot, [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FNiagaraHierarchyRootViewModel](API\Plugins\NiagaraEditor\ViewModels\HierarchyEditor\FNiagaraHierarch-_9) > SourceRootViewModel )