public class CompositeTreeTransformer
A TreeTransformer that applies component TreeTransformers in order.
The order in which they are applied is the order in which they are added or
the order in which they appear in the List passed to the constructor.
Does whatever one needs to do to a particular tree.
This routine is passed a whole Tree, and could itself
work recursively, but the canonical usage is to invoke this method
via the Tree.transform() method, which will apply the
transformer in a bottom-up manner to each local Tree,
and hence the implementation of TreeTransformer should
merely examine and change a local (one-level) Tree.