SMTP und Mail

<?xml version="1.0" encoding="UTF-8"?>
        <project xmlns="http://maven.apache.org/POM/4.0.0"
                 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
            <modelVersion>4.0.0</modelVersion>
            <parent>
                <groupId>at.aydin.academy</groupId>
                <artifactId>33smtpmail-pair</artifactId>
                <version>1.0.0</version>
                <relativePath>../pom.xml</relativePath>
            </parent>
            <artifactId>jakarta-mail-modern</artifactId>
            <packaging>jar</packaging>
            <name>Jakarta Mail Modern</name>

            <dependencies>
                <dependency><groupId>org.eclipse.angus</groupId><artifactId>jakarta.mail</artifactId><version>2.0.3</version></dependency>
<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
</dependency>

            </dependencies>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-compiler-plugin</artifactId>
                    </plugin>

                </plugins>
            </build>
        </project>

package at.aydin.lab.mail.modern;

import jakarta.mail.*;
import jakarta.mail.internet.*;
import java.util.*;

// Design Pattern: Gateway
// Zweck: Jakarta-Mail-API bleibt außerhalb des fachlichen Aufrufers.
public final class JakartaMailGateway {
    private final Session session;
    public JakartaMailGateway(Properties properties) {
        session = Session.getInstance(properties);
    }

    public MimeMessage prepare(MailCommand c) throws Exception {
        MimeMessage m = new MimeMessage(session);
        m.setFrom(new InternetAddress(c.from()));
        m.setRecipient(Message.RecipientType.TO, new InternetAddress(c.to()));
        m.setSubject(c.subject(), "UTF-8");
        m.setText(c.body(), "UTF-8");
        return m;
    }

    public void send(MailCommand c) throws Exception {
        Transport.send(prepare(c));
    }
}

package at.aydin.lab.mail.modern;

// Design Pattern: Command
// Zweck: Vollständiger Versandauftrag wird als unveränderliches Objekt übergeben.
public record MailCommand(String from, String to, String subject, String body) {
}

package at.aydin.lab.mail.modern;

import org.junit.jupiter.api.Test;
import java.util.*;
import static org.junit.jupiter.api.Assertions.assertEquals;

class JakartaMailGatewayTest {
    @Test
    void preparesWithoutSending() throws Exception {
        var g = new JakartaMailGateway(new Properties());
        assertEquals("Test", g.prepare(new MailCommand("a@example.test", "b@example.test", "Test", "Body")).getSubject());
    }
}