The following is with eslint-plugin-react@6.10.3.

If a propType is quoted for some reason like this:

MyComponent.propTypes = { 'data-id': PropTypes.string, };

Then the require-default-props rule gives the following warning:

propType "undefined" is not required, but has no corresponding defaultProp declaration. 

Howwever, giving the propType a default value like this does satisfy the rule:

MyComponent.defaultProps = { 'data-id': 'test', };

It seems like this is an issue with the formatting of the error message.