addTargets

This method adds views as targets to the transition, but only if the transition doesn't already have a target. It is best for views to contain one View object that does not exist in the view hierarchy (state.nonExistentView) so that when they are removed later, a list match will suffice to remove the targets. Otherwise, if you happened to have targeted the exact views for the transition, the replaceTargets call will remove them unexpectedly.