imyaman

@Entity
class Calendar extends AbstractAggregateRoot {
    CalendarEntry scheduleCalendarEntry(...) {
        CalendarEntry calendarEntry = new CalendarEntry(...);
        this.registerEvent(new CalendarEntryScheduled(...));
        return calendarEntry;
    }
}

@Entity
class Forum extends AbstractAggregateRoot {
    Discussion startDiscussion(
        DiscussionId discussionId,
        Author author,
        String subject) {

        if (this.isClosed()) {
            throw new IllegalStateException("Forum is closed");
        }
        Discussion discussion = new Discussion(
            this.tenant(),
            this.forumId(),
            discussionId,
            author,
            subject);
        registerEvent(new DiscussionStarted(...));
        return discussion;
    }
}

package com.saasovation.collaboration.domain.model.collaborator;

interface CollaboratorSerice {
    Author authorFrom(Tenant tenant, String identity);

    Creator creatorFrom(Tenant tenant, String identity);

    Moderator moderatorFrom(Tenant tenant, String identity);

    Owner ownerFrom(Tenant tenant, String identity);

    Participant participantFrom(Tenant tenant, String identity);
}

// infrastructure.services !!!
package com.saasovation.collaboration.infrastructure.services;

class UserRoleToCollaborationService implements CollaboratorSerice {
    @Override
    public Author authorFrom(Tenant tenant, String identity) {
        return (Author) userInRoleAdapter.toCollaborator(
            tenant, identity, "Author", Author.class);
        )
    }
}

package com.saasovation.collaboration.domain.model.collaborator;

class Author extends Collaborator {
    ...
}