public static Map<String, String> resolveAll(Map<String, String> properties) {
    return resolveAll(System.getenv(), properties);
  }
@Test
  public void testEnvironmentSubstitution() {
    Optional<Map.Entry<String, String>> envEntry = System.getenv().entrySet().stream().findFirst();
    Assumptions.assumeTrue(
        envEntry.isPresent(), "Expecting at least one env. variable to be present");
    Map<String, String> resolvedProps =
        EnvironmentUtil.resolveAll(ImmutableMap.of("env-test", "env:" + envEntry.get().getKey()));
    assertThat(resolvedProps)
        .as("Should get the user from the environment")
        .isEqualTo(ImmutableMap.of("env-test", envEntry.get().getValue()));
  }