@Test
public void testGet() {

  this.map.put(LOWER_KEY, VALUE_1);
  this.map.put(UPPER_KEY, VALUE_2);
  assertThat(this.map.get(LOWER_KEY)).isEqualTo(VALUE_2);
  assertThat(this.map.get(UPPER_KEY)).isEqualTo(VALUE_2);
  assertThat(this.map.get(WRONG_KEY)).isNull();
}