@Test
	public void testCyclicDependencyProblem1() {
		try {
			union.add(union);
			Assert.fail("Shouldn't be able to add a union to itself.");
		}
		catch (IllegalArgumentException e) {
			// Should get an exception from adding the union to itself.
		}
		try {
			union.insert(0, union);
			Assert.fail("Shouldn't be able to insert a union into itself.");
		}
		catch (IllegalArgumentException e) {
			// Should get an exception from inserting the union to itself.
		}
	}
Test that a structure can't be added to itself.
Ghidra/Features/Base/src/test/java/ghidra/program/model/data/UnionDataTypeTest.java