@Test
	public void testGenerateChildren_WriteReference() throws Exception {

		//
		// Have a reference in the function to a place that is not another function, and the
		// reference is a write reference.  No call node is created.
		//

		builder.createMemoryReference(firstCalledFunctionAddress, "0x1000", RefType.WRITE,
			SourceType.USER_DEFINED);
		List<GTreeNode> children = node1.generateChildren(TaskMonitor.DUMMY);
		assertTrue(children.isEmpty());
	}
This test class is covering the various types of 'calls' a function can make, such as a
direct call instruction, or through a user-defined reference.   External calls are also a bit
tricky.   This test was created by following the code paths in {@link OutgoingCallNode}
and making sure that each path was followed.
Ghidra/Features/Base/src/test.slow/java/ghidra/app/plugin/core/calltree/OutgoingCallNodeTest.java