code: private static Optional<ICondition> asNotLessThan( JsonObject json)
      {
      return
        Optional.of( json)
        .filter( j -> j.containsKey( NOT_LESS_THAN_KEY))
        .map( j -> j.getJsonObject( NOT_LESS_THAN_KEY))
        .map( a -> new AssertNotLess( a.getString( PROPERTY_KEY), a.getInt( MIN_KEY)));
      }
docs: Returns the AssertNotLess condition represented by the given JSON object or an empty
  value if no such condition is found.