*
* Elements of <code>groupingDefinitions</code> are firstly transformed to
* {@link org.opendaylight.yangtools.yang.parser.util.TopologicalSort.Node
* Node} interfaces and then are sorted by
* {@link org.opendaylight.yangtools.yang.parser.util.TopologicalSort#sort(Set)
*
* Elements of <code>groupingDefinitions</code> are firstly transformed to
* {@link org.opendaylight.yangtools.yang.parser.util.TopologicalSort.Node
* Node} interfaces and then are sorted by
* {@link org.opendaylight.yangtools.yang.parser.util.TopologicalSort#sort(Set)