dataStoreParams.put("intKey", 999);
        assertEquals("999", dataStoreParams.getAsString("intKey", "defaultValue"));
    }

    // Test containsKey
    public void test_containsKey() {
        assertFalse(dataStoreParams.containsKey("key1"));

        dataStoreParams.put("key1", "value1");
        assertTrue(dataStoreParams.containsKey("key1"));

        dataStoreParams.put("key2", null);

        assertThat(map.containsValue("test2"), is(true));
        assertThat(map.containsValue("test3"), is(not(true)));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testContainsKey() throws Exception {
        assertThat(map.containsKey("2"), is(true));
        assertThat(map.containsKey("3"), is(not(true)));
        map.put("3", null);
        assertThat(map.containsKey("3"), is(true));
    }

    }
    assertInvariants(map);
  }

  @J2ktIncompatible // https://youtrack.jetbrains.com/issue/KT-58242/ undefined behavior (crash)
  public void testContainsKey() {
    Map<K, V> map;
    K unmappedKey;
    try {
      map = makePopulatedMap();
      unmappedKey = getKeyNotInPopulatedMap();
    } catch (UnsupportedOperationException e) {
      return;
    }