@Test
	public void testApplyFunctionDefaultStackLocalDiff() throws Exception {

		// 0x010048a3: created default stack local_1 in p2.

		Function function2 = p2.getFunctionManager().getFunctionAt(addr(p2, 0x010048a3));
		programBuilder2.createLocalVariable(function2, null, DataType.DEFAULT, 0x1);

		programMerge = new ProgramMergeManager(p1, p2);
		AddressSet diffAs = new AddressSet();
		diffAs.addRange(addr(0x010048a3), addr(0x010048a3));
		programMerge.setDiffFilter(new ProgramDiffFilter(ProgramDiffFilter.FUNCTION_DIFFS));
		programMerge.setMergeFilter(
			new ProgramMergeFilter(ProgramMergeFilter.FUNCTIONS, ProgramMergeFilter.REPLACE));
		assertEquals(diffAs, programMerge.getFilteredDifferences());
		programMerge.merge(diffAs, TaskMonitor.DUMMY);
		assertEquals(new AddressSet(), programMerge.getFilteredDifferences());
	}
Test that programMerge can determine that function default stack params are
different.
Ghidra/Features/Base/src/test.slow/java/ghidra/program/util/ProgramMerge3Test.java