[Solved]-Flowtype: Typehinting class based HOC component-Reactjs

// @flow
import React, { Component } from 'react';
import type { ComponentType } from 'react';

type Props = {
  x: string | void,    // <<== HERE
}

const withReferral = <PassedProps: {}>(
    WrappedComponent: ComponentType<PassedProps>
): ComponentType<$Diff<PassedProps, Props>> => {
  class withReferral extends Component<PassedProps> {
    render() {
      return (<WrappedComponent {...this.props} x={'test'} />);
    }
  }

  return withReferral;
};

export default withReferral;