@Test
	public void testApplyFunctionDefaultStackParamDiff() throws Exception {

		// 0x1002cf5: created default stack param in p2.
		int transactionID = p2.startTransaction("Test Transaction");
		Function function = p2.getFunctionManager().getFunctionAt(addr(p2, 0x1002cf5));
		Variable var = new ParameterImpl("variable", DataType.DEFAULT, 0x1c, p2);
		function.addParameter(var, SourceType.USER_DEFINED);
		p2.endTransaction(transactionID, true);

		programMerge = new ProgramMergeManager(p1, p2);
		AddressSet diffAs = new AddressSet();
		diffAs.addRange(addr(0x1002cf5), addr(0x1002cf5));
		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