public static String substVars(String val, PropertyContainer pc1) {
    return substVars(val, pc1, null);
  }
@Test
  public void detectCircularReferencesInDefault() {
    context.putProperty("A", "${B:-${A}}");
    expectedException.expect(IllegalArgumentException.class);
    expectedException.expectMessage("Circular variable reference detected while parsing input [${A} --> ${B} --> ${A}]");
    OptionHelper.substVars("${A}", context);
  }