@Test public void testToList() throws Exception {
		IntervalSet s = IntervalSet.of(20,25);
		s.add(50,55);
		s.add(5,5);
		String expecting = "[5, 20, 21, 22, 23, 24, 25, 50, 51, 52, 53, 54, 55]";
		String result = String.valueOf(s.toList());
		assertEquals(expecting, result);
	}
This case is responsible for antlr/antlr4#153.
https://github.com/antlr/antlr4/issues/153
tool-testsuite/test/org/antlr/v4/test/tool/TestIntervalSet.java