public String get(String key) {
        return properties.getProperty(key);
    }
@Test
    public void testGet_whenValueNotString() {
        // given a "compromised" Properties object
        Properties props = new Properties();
        props.put("key", 1);

        // HazelcastProperties.get returns null
        HazelcastProperties hzProperties = new HazelcastProperties(props);
        assertNull(hzProperties.get("key"));
    }