JdbcUserDetailsManager should implement UserDetailsPasswordService and have a property enableUpdatePassword that is false by default (to prevent migrations that might produce passwords that are too large for the current database schema). This would allow users to easily opt into migrating passwords with JDBC. The new method would look something like this:

public UserDetails updatePassword(UserDetails user, String newPassword) {
    UserDetails updated = User.withUserDetails(user).password(newPassword).build();
    updateUser(updated);
    return updated;
}