Wrap a {@code source} RandomAccess which is related to this by a{@link Mixed} {@code transformToSource}. This is for {@link Mixed} transformsthat feature a full mapping of source to target components. That is, there is no down-projection, no source component is discarded. In this case, the current position can be recovered from the position of the source RandomAccess. Localize can be implemented via localize on the source RandomAccess.
For the general case, see {@link MixedRandomAccess}.
@param < T>
@author Tobias Pietzsch