What is the current behavior?
Currently, Transition and CSSTransition component files import prop-types as:
import * as PropTypes from 'prop-types';
What is the expected behavior?
All other components and files are importing prop-types in the expected way:
import PropTypes from 'prop-types';
I think a simple PR to just update these two files would suffice so there's consistent importing and usage of prop-types throughout.