@Test
public void testAdd() {

    metadata.commit(() -> {
        List<String> list = getList("prop1");
        boolean result = list.add("x");
        result |= list.add("y");
        
        assertThat(result).isTrue();
    }, MetadataAccess.SERVICE);
    
    metadata.read(() -> {
        List<String> list = getList("prop1");
        
        assertThat(list).contains("a", "b", "c", "x", "y");
    }, MetadataAccess.SERVICE);
}