public void makeParentMutable(TermItem item) {
        CompositeItem parent = item.getParent();
        CompositeItem mutable = convertSegmentItem(parent);
        if (parent != mutable) {
            CompositeItem parentsParent = parent.getParent();
            insertMutableInTree(mutable, parent, parentsParent);
        }
    }
Convert The parent of this item into a mutable item. Note, this
may change the shape of the query tree. (E.g. if the original parent is a
segment phrase, and the original parent's parent is a phrase, the terms
from the parent will be moved to the parent's parent.)

@param item the item for which the parent shall be made mutable
container-search/src/main/java/com/yahoo/prelude/semantics/engine/Evaluation.java