public String getDisplayableLocalSocketAddress() {
        return (this.bindAddress == null ? "*" : this.bindAddress) + ":" + this.port;
    }
Create a SSL socket that wraps the existing socket. This method is called
after the client issued the STARTTLS command.
<p>
Subclasses may override this method to configure the key stores, enabled
protocols/ cipher suites, enforce client authentication, etc.

@param socket the existing server socket
@return a SSLSocket
@throws IOException when creating the socket failed
src/main/java/de/gessnerfl/fakesmtp/smtp/server/BaseSmtpServer.java