code: public B activationCondition(String conditionExpression) {
      ActivationCondition activationCondition = createInstance(ActivationCondition.class);
      activationCondition.setTextContent(conditionExpression);
      element.setActivationCondition(activationCondition);
      return myself;
    }
docs: Sets the activation condition expression for the build complex gateway
  
  @param conditionExpression  the activation condition expression to set
  @return the builder object