@Override
    public Map<String, String> properties() {
        return Collections.unmodifiableMap(systemPropertiesConfigParser.parse(systemPropertiesProvider.get()));
    }
@Test
    public void testNonStringSystemPropertyValue() {
        String key = getClass().getSimpleName();
        systemProperties.put(key, true);
        assertNull(provider.properties().get(key));
    }