Apr 20, 2018 4:43:01 PM com.google.common.eventbus.EventBus$LoggingHandler handleException
SEVERE: Exception thrown by subscriber method onServerMessageEvent(core.traction.event.ServerMessageEvent) on subscriber core.traction.server.jetty.Me
ssageRouter@xxxxxxxx when dispatching event: core.traction.event.ServerMessageEvent@xxxxxxxx

    /**
     * Represents a role that one or more Users can have with
     * respect to an, and provides a mapping from an Entry to a
     * UserSet.
     *
     * @author Dave Shepperton
     */
    public static interface UserRole {

        /**
         * Returns a Function that provides a mapping from an
         * Entry to a UserSet reflecting the
         * Users who have this role for the Entry.
         */
        public Function<Entry,UserSet> entryToUsers();

    }

    public static enum StandardIntrinsicUserRole implements UserRole {

        /**
         * The contributors to an Entry.
         */
        CONTRIBUTORS,

        /**
         * The users mentioned in an Entry's content.
         */
        MENTIONED;

    }

    public static enum StandardAuthoredUserRole implements UserRole {

        /**
         * Users who are considered the assignees for an entry that
         * represents a task.
         */
        ASSIGNEES,

        /**
         * Users who are considered the invitees for an entry that
         * represents an event.
         */
        INVITEES,

        /**
         * Users who are considered members for an entry that supports
         * some sort of membership, such as projects.
         */
        MEMBERS,

        /**
         * Users who are considered owners for an entry that supports
         * some sort of ownership, such as projects.
         */
        OWNERS,

        /**
         * Users who have been subscribed to instant notifications of
         * activity by an entry author or editor.
         */
        SUBSCRIBERS;

    }

    public Set<User> getUsers(Entry entry, Entry.StandardAuthoredUserRole role);

    public Set<User> getUsersAssigned(Entry entry);

    public Set<User> getUsersInvited(Entry entry);

    public Set<User> getUsersMembers(Entry entry);

    public Set<User> getUsersOwners(Entry entry);

    public Set<User> getUsersSubscribed(Entry entry);

    public UserSet getAssignees();

    public UserSet getInvitees();

    public UserSet getMembers();

    public UserSet getOwners();

    // This will likely be changed to "getSubscribers"
    public UserSet getAutomaticSubscribers();