@Override
    public String toString() {
        return MoreObjects.toStringHelper(this)
                          .add("type", authorizationType)
                          .add("source",
                               authorizationSupplier != null ? "authorization"
                                                             : credentialsSupplier != null ? "credentials"
                                                                                           : null)
                          .toString();
    }
Converts this {@link ClientAuthorization} to a {@link ClientAuthentication}.
oauth2/src/main/java/com/linecorp/armeria/common/auth/oauth2/ClientAuthorization.java