Currently, Client cannot properly derive clone, because none of the EndpointState types implement clone. For example, trying to use openidconnect's CoreClient in a context that requires it to be Clone produces the following error:

the trait bound openidconnect::EndpointSet: Clone is not satisfied
required for Client<EmptyAdditionalClaims, ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ..., ...> to implement Clone