@Test
public void acceptClientCertificate() {

    final Connection connection = createConnection(CONNECTION_ID).toBuilder()
            .credentials(ClientCertificateCredentials.newBuilder()
                    .clientKey(Certificates.CLIENT_KEY)
                    .clientCertificate(Certificates.CLIENT_CRT)
                    .build())
            .build();
    final ConnectionValidator underTest = getConnectionValidator();
    underTest.validate(connection, DittoHeaders.empty(), actorSystem);
}