private boolean currentGroupExists() {
    for (NewlineGroup group = myCurrentGroup; group != myRootGroup; group = group.myParent) {
      if (!group.myParent.myChildren.contains(group)) {
        return false;
      }
    }
    return true;
  }
Recursive reformatting of groups.
If the group's content would take you over the specified preferred line length, then the group is applied.

- This algorithm usually ensures that if a group is applied, then all the group's parents in the tree are also
  applied. This tends to produce a nice structured output with well-placed potential newlines.
- The formatter keeps track of the offset as a result of the reformat at each character in the text buffer, and
  applies them to the bytecode offsets afterwards, so that the line number mappings don't get messed up.
src/org/jetbrains/java/decompiler/util/TextBuffer.java