public static void secure(String keystoreFile,
                              String keystorePassword,
                              String certAlias,
                              String truststoreFile,
                              String truststorePassword) {
        getInstance().secure(keystoreFile, keystorePassword, certAlias, truststoreFile, truststorePassword);
    }
Set the connection to be secure, using the specified keystore and
truststore. This has to be called before any route mapping is done. You
have to supply a keystore file, truststore file is optional (keystore
will be reused).
This method is only relevant when using embedded Jetty servers. It should
not be used if you are using Servlets, where you will need to secure the
connection in the servlet container

@param keystoreFile       The keystore file location as string
@param keystorePassword   the password for the keystore
@param certAlias          the default certificate Alias
@param truststoreFile     the truststore file location as string, leave null to reuse
                          keystore
@param truststorePassword the trust store password
src/main/java/spark/Spark.java