code: public static Optional<String> getAttributeAsString(final JsonObject aJsonObject,
            final String aAttributeName) {
      if (aJsonObject.has(aAttributeName)) {
        final JsonElement aElement = aJsonObject.get(aAttributeName);
        if (!aElement.isJsonNull()) {
          return Optional.of(aElement.getAsString());
        }
      }
  
      return Optional.empty();
    }
docs: Gets the value of an attribute
  
  @param aJsonObject the object
  @param aAttributeName the name of the attribute
  @return the value of the attribute, if it exists, else Optional.empty