code: public RolloutGroupConditionBuilder successAction(final RolloutGroupSuccessAction action, final String expression) {
          conditions.setSuccessAction(action);
          conditions.setSuccessActionExp(expression);
          return this;
      }
docs: Sets the success action and expression on the builder.
  
  @param action
  the success action
  @param expression
  the error expression
  @return the builder itself