@Override
    FieldPathIteratorHandler.ModificationStatus iterateNested(FieldPath fieldPath, int pos, FieldPathIteratorHandler handler) {
        FieldPathIteratorHandler.ModificationStatus status = map.iterateNested(fieldPath, pos, handler, this);
        return status;
    }
Uses toString() from the encapsulated Map.

@return the toString() of this set
document/src/main/java/com/yahoo/document/datatypes/WeightedSet.java