@Test
	public void testAsMapHeadFirst() {
		populateStore(-3, -1, 1, 3);

		assertEquals(-3, doTestMap(map.headMap(-2L, true), NavigableMap::firstKey, //
			NavigableMap::firstEntry).longValue());
		assertEquals(-3, doTestMap(map.headMap(-3L, true), NavigableMap::firstKey, //
			NavigableMap::firstEntry).longValue());
		assertNull(doTestMap(map.headMap(-3L, false), NavigableMap::firstKey, //
			NavigableMap::firstEntry));
		assertNull(doTestMap(map.headMap(-4L, true), NavigableMap::firstKey, //
			NavigableMap::firstEntry));

		assertEquals(3, doTestMap(rMap.headMap(2L, true), NavigableMap::firstKey, //
			NavigableMap::firstEntry).longValue());
		assertEquals(3, doTestMap(rMap.headMap(3L, true), NavigableMap::firstKey, //
			NavigableMap::firstEntry).longValue());
		assertNull(doTestMap(rMap.headMap(3L, false), NavigableMap::firstKey, //
			NavigableMap::firstEntry));
		assertNull(doTestMap(rMap.headMap(4L, true), NavigableMap::firstKey, //
			NavigableMap::firstEntry));
	}
This exists to verify behavior in {@link #testAsValuesSubIterator()}
Ghidra/Debug/ProposedUtils/src/test/java/ghidra/util/database/DBCachedObjectStoreTest.java