/**
  * Allows to register given wrap as a parent of the current wrap.
  *
  * <p><code>'Parent'</code> wrap registration here means that {@link #isChildOf(WrapImpl,
  * LeafBlockWrapper)} returns <code>'true'</code> if given wrap is used as a <code>'parent'</code>
  * argument.
  *
  * @param parent parent wrap to register for the current wrap
  */
 void registerParent(@Nullable WrapImpl parent) {
   if (parent == this) return;
   if (parent == null) return;
   if (parent.isChildOf(this, null)) return;
   if (myParents == emptyParentsSet) myParents = new HashSet<WrapImpl>(5);
   myParents.add(parent);
 }
 public boolean isChildOf(@Nullable final WrapImpl wrap, LeafBlockWrapper leaf) {
   if (getIgnoreParentWraps()) return false;
   if (leaf != null && myIgnoredWraps != null) {
     Collection<LeafBlockWrapper> leaves = myIgnoredWraps.get(wrap);
     if (leaves != null && leaves.contains(leaf)) {
       return false;
     }
   }
   for (WrapImpl parent : myParents) {
     if (parent == wrap) return true;
     if (parent.isChildOf(wrap, leaf)) return true;
   }
   return false;
 }