public CertificateBuilder sanDnsNames(String... hostNames) throws IOException {
            if (hostNames.length > 0) {
                GeneralName[] altNames = new GeneralName[hostNames.length];
                for (int i = 0; i < hostNames.length; i++)
                    altNames[i] = new GeneralName(GeneralName.dNSName, hostNames[i]);
                subjectAltName = GeneralNames.getInstance(new DERSequence(altNames)).getEncoded();
            } else {
                subjectAltName = null;
            }
            return this;
        }
Creates a keystore with a single key and saves it to a file.

@param filename String file to save
@param password String store password to set on keystore
@param keyPassword String key password to set on key
@param alias String alias to use for the key
@param privateKey Key to save in keystore
@param cert Certificate to use as certificate chain associated to key
@throws GeneralSecurityException for any error with the security APIs
@throws IOException if there is an I/O error saving the file
clients/src/test/java/org/apache/kafka/test/TestSslUtils.java