void () { final DiffElement<?> src = getSource(); final DiffElement<?> trg = getTarget(); if (src instanceof ComparableDiffElement) { ((ComparableDiffElement)src).prepare(trg); } if (trg instanceof ComparableDiffElement) { ((ComparableDiffElement)trg).prepare(src); } for (DTree tree : getChildren()) { tree.prepare(); } }