refactored code resulting from the same prompt using Junie + Gemini Flash 3

Course.java

package course_duration.domain;

import java.time.Duration;
import java.time.Instant;
import java.time.temporal.ChronoUnit;

public class Course {
    private static final Duration MAX_MINUTES_SHORT_COURSES = Duration.ofMinutes(10);
    private final String name;
    private final Configuration configuration;
    private final Clock clock;
    private Duration durationInMinutes;
    private final CourseView courseView;
    private CourseState state;

    public Course(String name, Configuration configuration, Clock clock, CourseView courseView) {
        this.name = name;
        this.configuration = configuration;
        this.clock = clock;
        this.courseView = courseView;
        durationInMinutes = Duration.ofMinutes(0);
        this.state = new YetToStartCourseState(clock, configuration, courseView).attach(this);
    }

    public void showDetails() {
        state.showDetails();
    }

    public void start() {
        state = state.start();
    }

    public void end() {
        state = state.end();
    }

    boolean isShort() {
        return durationInMinutes.compareTo(MAX_MINUTES_SHORT_COURSES) < 0;
    }

    String getTitle() {
        return name + " course in " + getCollege() + " college";
    }

    Duration getDurationInMinutes() {
        return durationInMinutes;
    }

    void setDurationInMinutes(Duration durationInMinutes) {
        this.durationInMinutes = durationInMinutes;
    }

    Configuration getConfiguration() {
        return configuration;
    }

    Clock getClock() {
        return clock;
    }

    CourseView getCourseView() {
        return courseView;
    }

    private String getCollege() {
        String college = configuration.getValue("COLLEGE");
        if (college == null) {
            return "not found";
        }
        return college;
    }
}

CourseState.java

package course_duration.domain;

import java.time.Duration;

abstract class CourseState {
    protected final Clock clock;
    protected final Configuration configuration;
    protected final CourseView courseView;
    protected Course course;

    protected CourseState(Clock clock, Configuration configuration, CourseView courseView) {
        this.clock = clock;
        this.configuration = configuration;
        this.courseView = courseView;
    }

    public CourseState attach(Course course) {
        this.course = course;
        return this;
    }

    public void showDetails() {
        this.courseView.displayLine("Title: " + course.getTitle());
        Duration duration = course.getDurationInMinutes();
        this.courseView.displayLine("Duration: " + duration.toMinutes() + " minutes");
        this.courseView.displayLine("Type: " + (course.isShort() ? "short" : "long"));
    }

    public abstract CourseState start();

    public abstract CourseState end();
}

FinishedCourseState.java

package course_duration.domain;

import java.time.Duration;

class FinishedCourseState extends CourseState {
    private final Duration durationInMinutes;

    FinishedCourseState(Duration durationInMinutes, Clock clock, Configuration configuration, CourseView courseView) {
        super(clock, configuration, courseView);
        this.durationInMinutes = durationInMinutes;
    }

    @Override
    public CourseState start() {
        // Final state; no transitions
        return this;
    }

    @Override
    public CourseState end() {
        // Final state; no transitions
        return this;
    }
}

OnGoingCourseState.java

package course_duration.domain;

import java.time.Duration;
import java.time.Instant;
import java.time.temporal.ChronoUnit;

class OnGoingCourseState extends CourseState {
    private final Instant startTime;

    OnGoingCourseState(Instant startTime, Clock clock, Configuration configuration, CourseView courseView) {
        super(clock, configuration, courseView);
        this.startTime = startTime;
    }

    @Override
    public CourseState start() {
        // Already started
        return this;
    }

    @Override
    public CourseState end() {
        Instant endTime = clock.now();
        Duration duration = Duration.ofMinutes(ChronoUnit.MINUTES.between(startTime, endTime));
        course.setDurationInMinutes(duration);
        return new FinishedCourseState(duration, clock, configuration, courseView).attach(course);
    }
}

YetToStartCourseState.java

package course_duration.domain;

class YetToStartCourseState extends CourseState {
    YetToStartCourseState(Clock clock, Configuration configuration, CourseView courseView) {
        super(clock, configuration, courseView);
    }

    @Override
    public CourseState start() {
        return new OnGoingCourseState(clock.now(), clock, configuration, courseView).attach(course);
    }

    @Override
    public CourseState end() {
        // No change in duration, remains zero
        return this;
    }
}