@Test
	public void testCyclicDependencyProblem3() {
		TypeDef typeDef = createTypeDef(union);
		try {
			union.add(typeDef);
			Assert.fail("Shouldn't be able to add a union typedef to the typedef's union.");
		}
		catch (IllegalArgumentException e) {
			// Should get an exception from adding the union to itself.
		}
		try {
			union.insert(0, typeDef);
			Assert.fail("Shouldn't be able to insert a union typedef into the typedef's union.");
		}
		catch (IllegalArgumentException e) {
			// Should get an exception from inserting the union to itself.
		}
	}
Test that a typedef of a union can't be added to the union.
Ghidra/Features/Base/src/test/java/ghidra/program/model/data/UnionDataTypeTest.java