https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticAnimationEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticAnimationEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticClipboardEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticClipboardEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticCompositionEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticCompositionEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticDragEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticDragEvent.js
https://facebook.github.io/react/docs/events.html
https://facebook.github.io/react/docs/events.html
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticFocusEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticFocusEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticKeyboardEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticKeyboardEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticMouseEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticMouseEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticPointerEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticPointerEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticTouchEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticTouchEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticTransitionEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticTransitionEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticUIEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticUIEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticWheelEvent.js
https://github.com/facebook/react/blob/master/packages/react-dom/src/events/SyntheticWheelEvent.js
See https://flow.org/en/docs/react/types