public Map<String, String> getPropertiesWithPrefix(String prefix) {
    return getPropertiesWithPrefix(prefix, false);
  }
@Test
  public void testGetPropertiesWithPrefixEmptyResult() {
    ConfigurationProperties configurationProperties =
        new ConfigurationProperties(PROPERTIES);

    Map<String, String> propsEmptyPrefix = configurationProperties.getPropertiesWithPrefix("");
    Map<String, String> propsLongPrefix = configurationProperties
        .getPropertiesWithPrefix("root.1.2.4.5.6");
    Map<String, String> propsNonExistingRootPrefix = configurationProperties
        .getPropertiesWithPrefix("3");

    Assert.assertEquals(0, propsEmptyPrefix.size());
    Assert.assertEquals(0, propsLongPrefix.size());
    Assert.assertEquals(0, propsNonExistingRootPrefix.size());
  }