@Test
    void testPropertiesAsMap() {
        Properties props = new Properties();
        props.setProperty("foo1", "bar1");
        props.setProperty("foo2", "bar2");
        PropertiesAsMap pam = new PropertiesAsMap(props);
        assertEquals(2, pam.size());
        Set<Entry<String, String>> set = pam.entrySet();
        assertNotNull(set);
        assertEquals(2, set.size());

    @Override
    public Map<String, String> getUserProperties() {
        return Collections.unmodifiableMap(new PropertiesAsMap(getMavenSession().getUserProperties()));
    }

    @Nonnull
    @Override
    public Map<String, String> getSystemProperties() {
        return Collections.unmodifiableMap(new PropertiesAsMap(getMavenSession().getSystemProperties()));
    }

    @Nonnull
    @Override