HOC as a function won't get generated docs

Similar to #177 but a slightly different scenario...

Given a HOC method like so:

import { bool } from 'prop-types';

const withSomeExtraProps = Wrapped => {
  class HigherOrderComponent extends Component  {
    static propTypes = Object.assign({}, Wrapped.propTypes, {
      /**
       * This should be picked up in the docgenInfo
       */
      anExtraProp: bool,
    });
    static defaultProps = Object.assign({}, Wrapped.defaultProps, {
      anExtraProp: false,
    });
    // ....the rest of the HOC logic
  }
  return HigherOrderComponent;
}

export default withSomeExtraProps;

I understand that this wouldn't automatically mean that the export default withSomeExtraProps(Wrapped) wouldn't automatically get the docgenInfo from the HOC added, but I thought individually this HOC would have it's own docgenInfo that I could reference on it's own.

However, it seems the inner component class here doesn't get recognised and parsed. Does the component class need to be exported for the parser to find it?

Start by reproducing the HOC example in the issue and trace how the parser handles the inner component class. Confirm the expected docgenInfo behavior and add coverage showing that the HOC's extra prop is recognized; the report names no files or existing tests.