How to make the class not disappear (ReactCSSTransitionGroup)?

Question

React

<ReactCSSTransitionGroup
              transitionName="example"
              transitionAppear={true}
              transitionAppearTimeout={1000}
              transitionEnter={false}
              transitionLeave={false}>
              <h1>Fading at Initial Mount</h1>
            </ReactCSSTransitionGroup>

.example-appear {
  opacity: 0.01;
}

.example-appear.example-appear-active {
  opacity: 1;
  transition: opacity .5s ease-in;
}

In a second, the class disappears completely.