code: public static String subst(final String value, final Properties props) {
          try {
              return OptionConverter.substVars(value, props);
          } catch (IllegalArgumentException e) {
              LogLog.warn("Could not perform variable substitution.", e);
              return value;
          }
      }
docs: Substitutes property value for any references in expression.
  
  @param value value from configuration file, may contain
  literal text, property references or both
  @param props properties.
  @return evaluated expression, may still contain expressions
  if unable to expand.
  @since 1.2.15