@Test public void computeIfAbsentWithExistingValue() { assertNull(map.putIfAbsent("key", "value1")); assertEquals("value1", map.putIfAbsent("KEY", "value2")); assertEquals("value1", map.put("Key", "value3")); assertEquals("value3", map.computeIfAbsent("key", key -> "value1")); assertEquals("value3", map.computeIfAbsent("KEY", key -> "value2")); assertEquals("value3", map.computeIfAbsent("Key", key -> "value3")); }