@Test
public void testGetPropertiesOf() throws Exception {

    Map<String, String> properties = asMap(
            "root.my.a", "valueA",
            "root.my.b", "valueB",
            "your.x", "valueX"
    );
    Map<String, String> subProps = PropertiesExt.getPropertiesOf("root.my", properties);
    assertThat(subProps).containsAllEntriesOf(asMap("a", "valueA", "b", "valueB"));
}