public static String substVars(String val, PropertyContainer pc1) {
    return substVars(val, pc1, null);
  }
@Test
  public void trailingColon_LOGBACK_1140() {
    String prefix = "c:";
    String suffix = "/tmp";
    context.putProperty("var", prefix);
    String r = OptionHelper.substVars("${var}" + suffix, context);
    assertEquals(prefix + suffix, r);
  }