### Question:
FileCertificateRepo implements CertificateRepo { public String convertIdForFileSystem(String dn) { String result = dn.replace("=", "-"); result = result.replace(", ", "_"); result = result.replace(",", "_"); result = result.replace("/", "_"); result = result.replace("\\", "_"); result = result.replace("{", "_"); result = result.replace("}", "_"); result = result.replace(":", "_"); return result; } FileCertificateRepo(String path); void saveCertificate(X509Certificate cert, UseKeyWithType id); void saveTrustedCACertificate(X509Certificate cert, UseKeyWithType id); void saveCACertificate(X509Certificate cert, UseKeyWithType id); void saveCRL(X509CRL crl, UseKeyWithType id); String convertIdForFileSystem(String dn); String getCertPath(X509Certificate cert, UseKeyWithType id); X509Certificate readCertificate(File certFile); X509CRL readCRL(File crlFile); @Override List<X509Certificate> getTrustedCaCerts(); @Override List<X509Certificate> getCaCerts(); @Override List<X509CRL> getCRLs(); @Override X509Certificate findByServiceName(String serviceName); @Override X509Certificate findByEndpoint(String endpoint); @Override X509Certificate findBySubjectDn(String subjectDn); @Override X509Certificate findByIssuerSerial(String issuer, String serial);  }### Answer:
@Test public void testConvertDnForFileSystem() throws CertificateException { String convertedName = new FileCertificateRepo("src/test/resources/store1") .convertIdForFileSystem(EXAMPLE_SUBJECT_DN); assertEquals("CN-www.issuer.com_L-CGN_ST-NRW_C-DE_O-Issuer", convertedName); }