### Question:
ResourceGroupId { public boolean isAncestorOf(ResourceGroupId descendant) { List<String> descendantSegments = descendant.getSegments(); if (segments.size() >= descendantSegments.size()) { return false; } return descendantSegments.subList(0, segments.size()).equals(segments); } ResourceGroupId(String name);  ResourceGroupId(ResourceGroupId parent, String name); @JsonCreator  ResourceGroupId(List<String> segments); String getLastSegment(); @JsonValue List<String> getSegments(); ResourceGroupId getRoot(); Optional<ResourceGroupId> getParent(); boolean isAncestorOf(ResourceGroupId descendant); @Override String toString(); @Override boolean equals(Object o); @Override int hashCode();  }### Answer:
@Test public void testIsAncestor() { ResourceGroupId root = new ResourceGroupId("root"); ResourceGroupId rootA = new ResourceGroupId(root, "a"); ResourceGroupId rootAFoo = new ResourceGroupId(rootA, "foo"); ResourceGroupId rootBar = new ResourceGroupId(root, "bar"); assertTrue(root.isAncestorOf(rootA)); assertTrue(root.isAncestorOf(rootAFoo)); assertTrue(root.isAncestorOf(rootBar)); assertTrue(rootA.isAncestorOf(rootAFoo)); assertFalse(rootA.isAncestorOf(rootBar)); assertFalse(rootAFoo.isAncestorOf(rootBar)); assertFalse(rootBar.isAncestorOf(rootAFoo)); assertFalse(rootAFoo.isAncestorOf(root)); assertFalse(root.isAncestorOf(root)); assertFalse(rootAFoo.isAncestorOf(rootAFoo)); }