assertEquals("defaultValue", dataStoreParams.getAsString("nullKey", "defaultValue"));
    }

    // Test getAsString with default value and non-String value
    public void test_getAsStringWithDefaultValueAndNonStringValue() {
        dataStoreParams.put("intKey", 999);
        assertEquals("999", dataStoreParams.getAsString("intKey", "defaultValue"));
    }

    // Test containsKey