diff --git a/app/controllers/journals_controller.rb b/app/controllers/journals_controller.rb
index 8e7bcab40..4f37f0b09 100644
--- a/app/controllers/journals_controller.rb
+++ b/app/controllers/journals_controller.rb
@@ -46,7 +46,7 @@ class JournalsController < ApplicationController
   end
 
   def diff
-    @issue = @journal.issue
+    @issue = @journal.journalized
     if params[:detail_id].present?
       @detail = @journal.details.find_by_id(params[:detail_id])
     else
@@ -101,7 +101,7 @@ class JournalsController < ApplicationController
 
   def find_journal
     @journal = Journal.visible.find(params[:id])
-    @project = @journal.journalized.project
+    @project = @journal.project
   rescue ActiveRecord::RecordNotFound
     render_404
   end
diff --git a/app/helpers/journals_helper.rb b/app/helpers/journals_helper.rb
index 4092b7b0f..206df1d0c 100644
--- a/app/helpers/journals_helper.rb
+++ b/app/helpers/journals_helper.rb
@@ -30,7 +30,7 @@ module JournalsHelper
   def render_journal_actions(issue, journal, options={})
     links = []
     dropbown_links = []
-    indice = journal.indice || journal.issue.visible_journals_with_index.find{|j| j.id == journal.id}&.indice
+    indice = journal.indice || journal.journalized.visible_journals_with_index.find{|j| j.id == journal.id}&.indice
 
     dropbown_links << copy_object_url_link(issue_url(issue, anchor: "note-#{indice}", only_path: false))
     if journal.attachments.size > 1
diff --git a/app/models/issue.rb b/app/models/issue.rb
index fa2d7707d..416776e4a 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -38,7 +38,6 @@ class Issue < ApplicationRecord
   belongs_to :priority, :class_name => 'IssuePriority'
   belongs_to :category, :class_name => 'IssueCategory'
 
-  has_many :journals, :as => :journalized, :dependent => :destroy, :inverse_of => :journalized
   has_many :time_entries, :dependent => :destroy
   has_and_belongs_to_many :changesets, lambda {order("#{Changeset.table_name}.committed_on ASC, #{Changeset.table_name}.id ASC")}
 
@@ -48,6 +47,7 @@ class Issue < ApplicationRecord
   acts_as_attachable :after_add => :attachment_added, :after_remove => :attachment_removed
   acts_as_customizable
   acts_as_watchable
+  acts_as_journalized :activity_type => 'issues'
   acts_as_searchable :columns => ['subject', "#{table_name}.description"],
                      :preload => [:project, :status, :tracker],
                      :scope => lambda {|options| options[:open_issues] ? self.open : self.all}
@@ -1304,9 +1304,8 @@ class Issue < ApplicationRecord
   def self.load_visible_last_updated_by(issues, user=User.current)
     if issues.any?
       issue_ids = issues.map(&:id)
-      journal_ids = Journal.joins(issue: :project).
-        where(:journalized_type => 'Issue', :journalized_id => issue_ids).
-        where(Journal.visible_notes_condition(user, :skip_pre_condition => true)).
+      journals = journal_visibility_scope(Journal.where(journalized_type: 'Issue', journalized_id: issue_ids))
+      journal_ids = journal_notes_visibility_scope(journals, user, skip_pre_condition: true).
         group(:journalized_id).
         maximum(:id).
         values
@@ -1323,9 +1322,8 @@ class Issue < ApplicationRecord
   def self.load_visible_last_notes(issues, user=User.current)
     if issues.any?
       issue_ids = issues.map(&:id)
-      journal_ids = Journal.joins(issue: :project).
-        where(:journalized_type => 'Issue', :journalized_id => issue_ids).
-        where(Journal.visible_notes_condition(user, :skip_pre_condition => true)).
+      journals = journal_visibility_scope(Journal.where(journalized_type: 'Issue', journalized_id: issue_ids))
+      journal_ids = journal_notes_visibility_scope(journals, user, skip_pre_condition: true).
         where.not(notes: '').
         group(:journalized_id).
         maximum(:id).
@@ -1721,6 +1719,107 @@ class Issue < ApplicationRecord
     end
   end
 
+  def self.journal_activity_preload
+    [{ journalized: :project }, { journalized: :tracker }, :user]
+  end
+
+  def self.journal_activity_scope(scope)
+    scope.joins("LEFT OUTER JOIN #{JournalDetail.table_name} ON #{JournalDetail.table_name}.journal_id = #{Journal.table_name}.id").
+          where("#{JournalDetail.table_name}.prop_key = 'status_id' OR #{Journal.table_name}.notes <> ''").distinct
+  end
+
+  def journal_event_title(journal)
+    status = (s = journal_new_status(journal)) ? " (#{s})" : nil
+    "#{tracker} ##{id}#{status}: #{subject}"
+  end
+
+  def journal_event_type(journal)
+    status = journal_new_status(journal)
+    if status
+      status.is_closed? ? 'issue-closed' : 'issue-edit'
+    else
+      'issue-note'
+    end
+  end
+
+  def journal_event_url(journal)
+    {controller: 'issues', action: 'show', id: id, anchor: "change-#{journal.id}"}
+  end
+
+  def self.journal_visibility_scope(scope)
+    scope.joins("INNER JOIN #{Issue.table_name} ON #{Issue.table_name}.id = #{Journal.table_name}.journalized_id").
+          joins("INNER JOIN #{Project.table_name} ON #{Project.table_name}.id = #{Issue.table_name}.project_id")
+  end
+
+  def self.journal_notes_visibility_scope(scope, user, options = {})
+    scope.where(Journal.visible_notes_condition(user, options))
+  end
+
+  def journal_editable_by?(journal, usr)
+    usr && usr.logged? && (usr.allowed_to?(:edit_issue_notes, project) || (journal.user == usr && usr.allowed_to?(:edit_own_issue_notes, project)))
+  end
+
+  def journal_relation_visible?(detail, user)
+    Issue.find_by(id: detail.value || detail.old_value)&.visible?(user)
+  end
+
+  def journal_notify(journal)
+    return unless journal.notify?
+
+    if Setting.notified_events.include?('issue_updated') ||
+       (Setting.notified_events.include?('issue_note_added') && journal.notes.present?) ||
+       (Setting.notified_events.include?('issue_status_updated') && journal_new_status(journal).present?) ||
+       (Setting.notified_events.include?('issue_assigned_to_updated') && journal.detail_for_attribute('assigned_to_id').present?) ||
+       (Setting.notified_events.include?('issue_priority_updated') && journal.new_value_for('priority_id').present?) ||
+       (Setting.notified_events.include?('issue_fixed_version_updated') && journal.detail_for_attribute('fixed_version_id').present?) ||
+       (Setting.notified_events.include?('issue_attachment_added') &&
+         journal.details.any? {|d| d.property == 'attachment' && d.value })
+
+      Mailer.deliver_issue_edit(journal)
+    end
+  end
+
+  def journal_process_watchers(journal)
+    usr = journal.user
+    if usr.is_a?(User) &&
+       usr.pref.auto_watch_on?('issue_contributed_to') &&
+       journal.valid_watcher?(usr)
+      set_watcher(usr, true)
+    end
+
+    assignee = assigned_to
+    if assignee.is_a?(User) &&
+       assignee.pref.auto_watch_on?('issue_assigned_to_me') &&
+       journal.valid_watcher?(assignee)
+      set_watcher(assignee, true)
+    end
+  end
+
+  def self.journal_visible_scope(user = User.current, options = {})
+    joins(:project).where(visible_condition(user, options))
+  end
+
+  def journal_user_can_view_private_notes?(user)
+    user.allowed_to?(:view_private_notes, project)
+  end
+
+  def journal_private_notes_allowed?(user)
+    user.allowed_to?(:set_notes_private, project)
+  end
+
+  def journal_valid_watcher?(user)
+    user.active? &&
+      user.allowed_to?(:add_issue_watchers, project) &&
+      valid_watcher?(user) &&
+      !watched_by?(user)
+  end
+
+  # Returns the new status if the journal contains a status change, otherwise nil
+  def journal_new_status(journal)
+    s = journal.new_value_for('status_id')
+    s ? IssueStatus.find_by_id(s.to_i) : nil
+  end
+
   private
 
   def user_tracker_permission?(user, permission)
diff --git a/app/models/issue_query.rb b/app/models/issue_query.rb
index 3431750f6..1a5b47f4b 100644
--- a/app/models/issue_query.rb
+++ b/app/models/issue_query.rb
@@ -477,13 +477,13 @@ class IssueQuery < Query
   # Returns the journals
   # Valid options are :order, :offset, :limit
   def journals(options={})
-    Journal.visible.
-      joins(:issue => [:project, :status]).
+    Issue.journal_visibility_scope(
+      Journal.visible.where(journalized_type: 'Issue')).
       where(statement).
       order(options[:order]).
       limit(options[:limit]).
       offset(options[:offset]).
-      preload(:details, :user, {:issue => [:project, :author, :tracker, :status]}).
+      preload(:details, :user, {:journalized => [:project, :author, :tracker, :status]}).
       to_a
   rescue ::ActiveRecord::StatementInvalid => e
     raise StatementInvalid.new(e.message)
diff --git a/app/models/journal.rb b/app/models/journal.rb
index 1874feb0c..55ab62069 100644
--- a/app/models/journal.rb
+++ b/app/models/journal.rb
@@ -21,44 +21,43 @@ class Journal < ApplicationRecord
   include Redmine::SafeAttributes
   include Redmine::Reaction::Reactable
 
-  belongs_to :journalized, :polymorphic => true
-  # added as a quick fix to allow eager loading of the polymorphic association
-  # since always associated to an issue, for now
-  belongs_to :issue, :foreign_key => :journalized_id
-
+  belongs_to :journalized, :polymorphic => true, :inverse_of => :journals
   belongs_to :user
   belongs_to :updated_by, :class_name => 'User'
+
   has_many :details, :class_name => "JournalDetail", :dependent => :delete_all, :inverse_of => :journal
   attr_accessor :indice
 
+  cattr_accessor :journalized_types
+
+  def self.register_journalized_type(klass)
+    self.journalized_types ||= []
+    self.journalized_types << klass unless journalized_types.include?(klass)
+  end
+
+  def self.activity_scope_for(klass)
+    scope = where(journalized_type: klass.name)
+    scope = scope.preload(*klass.journal_activity_preload)
+    klass.journal_activity_scope(scope)
+  end
+
+  def self.register_activity_provider(klass)
+    return if klass.journal_activity_type.blank?
+
+    acts_as_activity_provider(
+      type: klass.journal_activity_type,
+      author_key: :user_id,
+      scope: proc { activity_scope_for(klass) }
+    )
+  end
+
   acts_as_event(
-    :title =>
-       Proc.new do |o|
-         status = ((s = o.new_status) ? " (#{s})" : nil)
-         "#{o.issue.tracker} ##{o.issue.id}#{status}: #{o.issue.subject}"
-       end,
-    :description => :notes,
-    :author => :user,
-    :group => :issue,
-    :type =>
-      Proc.new do |o|
-        (s = o.new_status) ? (s.is_closed? ? 'issue-closed' : 'issue-edit') : 'issue-note'
-      end,
-    :url =>
-      Proc.new do |o|
-        {:controller => 'issues', :action => 'show', :id => o.issue.id, :anchor => "change-#{o.id}"}
-      end
-  )
-  acts_as_activity_provider(
-    :type => 'issues',
-    :author_key => :user_id,
-    :scope =>
-      proc do
-        preload({:issue => :project}, {:issue => :tracker}, :user).
-          joins("LEFT OUTER JOIN #{JournalDetail.table_name} ON #{JournalDetail.table_name}.journal_id = #{Journal.table_name}.id").
-            where("#{Journal.table_name}.journalized_type = 'Issue' AND" +
-                  " (#{JournalDetail.table_name}.prop_key = 'status_id' OR #{Journal.table_name}.notes <> '')").distinct
-      end
+    title: proc {|o|  o.journalized.journal_event_title(o) },
+    description: :notes,
+    author: :user,
+    group: :journalized,
+    type: proc {|o| o.journalized.journal_event_type(o) },
+    url: proc {|o| o.journalized.journal_event_url(o) }
   )
   acts_as_mentionable :attributes => ['notes']
   before_create :split_private_notes
@@ -68,10 +67,16 @@ class Journal < ApplicationRecord
   scope :visible, (lambda do |*args|
     user = args.shift || User.current
     options = args.shift || {}
-
-    joins(:issue => :project).
-      where(Issue.visible_condition(user, options)).
-      where(Journal.visible_notes_condition(user, :skip_pre_condition => true))
+    visible_scope = none
+
+    journalized_types.each do |klass|
+      relation = where(journalized_type: klass.name)
+      relation = klass.journal_visibility_scope(relation)
+      relation = relation.where(journalized_id: klass.journal_visible_scope(user, options).select(:id))
+      relation = klass.journal_notes_visibility_scope(relation, user, options)
+      visible_scope = visible_scope.or(relation)
+    end
+    visible_scope
   end)
 
   safe_attributes(
@@ -79,7 +84,7 @@ class Journal < ApplicationRecord
     :if => lambda {|journal, user| journal.new_record? || journal.editable_by?(user)})
   safe_attributes(
     'private_notes',
-    :if => lambda {|journal, user| user.allowed_to?(:set_notes_private, journal.project)})
+    :if => lambda {|journal, user| journal.journalized.journal_private_notes_allowed?(user)})
   safe_attributes 'updated_by'
 
   # Returns a SQL condition to filter out journals with notes that are not visible to user
@@ -109,22 +114,13 @@ class Journal < ApplicationRecord
     notes.blank? && details.empty?
   end
 
-  def journalized
-    if journalized_type == 'Issue' && association(:issue).loaded?
-      # Avoid extra query by using preloaded association
-      issue
-    else
-      super
-    end
-  end
-
   # Returns journal details that are visible to user
   def visible_details(user=User.current)
     details.select do |detail|
       if detail.property == 'cf'
         detail.custom_field && detail.custom_field.visible_by?(project, user)
       elsif detail.property == 'relation'
-        Issue.find_by_id(detail.value || detail.old_value).try(:visible?, user)
+        journalized.journal_relation_visible?(detail, user)
       else
         true
       end
@@ -137,10 +133,8 @@ class Journal < ApplicationRecord
     details.detect {|detail| detail.prop_key == attribute}
   end
 
-  # Returns the new status if the journal contains a status change, otherwise nil
   def new_status
-    s = new_value_for('status_id')
-    s ? IssueStatus.find_by_id(s.to_i) : nil
+    journalized.journal_new_status(self)
   end
 
   def new_value_for(prop)
@@ -148,11 +142,11 @@ class Journal < ApplicationRecord
   end
 
   def editable_by?(usr)
-    usr && usr.logged? && (usr.allowed_to?(:edit_issue_notes, project) || (self.user == usr && usr.allowed_to?(:edit_own_issue_notes, project)))
+    journalized.journal_editable_by?(self, usr)
   end
 
   def project
-    journalized.respond_to?(:project) ? journalized.project : nil
+    journalized.journal_project
   end
 
   def attachments
@@ -163,7 +157,7 @@ class Journal < ApplicationRecord
   end
 
   def visible?(*)
-    journalized.visible?(*)
+    journalized.journal_visible?(*)
   end
 
   def attachments_visible?
@@ -188,9 +182,9 @@ class Journal < ApplicationRecord
   end
 
   def notified_users
-    notified = journalized.notified_users
+    notified = journalized.journal_notified_users
     if private_notes?
-      notified = notified.select {|user| user.allowed_to?(:view_private_notes, journalized.project)}
+      notified = select_journal_visible_user(notified)
     end
     notified
   end
@@ -200,7 +194,7 @@ class Journal < ApplicationRecord
   end
 
   def notified_watchers
-    notified = journalized.notified_watchers
+    notified = journalized.journal_notified_watchers
     select_journal_visible_user(notified)
   end
 
@@ -264,6 +258,10 @@ class Journal < ApplicationRecord
       )
   end
 
+  def valid_watcher?(user)
+    journalized.journal_valid_watcher?(user)
+  end
+
   private
 
   # Generates journal details for attribute and custom field changes
@@ -354,45 +352,16 @@ class Journal < ApplicationRecord
   end
 
   def add_watcher
-    if user.is_a?(User) &&
-       user.pref.auto_watch_on?('issue_contributed_to') &&
-       valid_watcher?(user)
-      journalized.set_watcher(user, true)
-    end
-
-    assignee = journalized.assigned_to
-    if assignee.is_a?(User) &&
-       assignee.pref.auto_watch_on?('issue_assigned_to_me') &&
-       valid_watcher?(assignee)
-      journalized.set_watcher(assignee, true)
-    end
-  end
-
-  def valid_watcher?(user)
-    user.active? &&
-      user.allowed_to?(:add_issue_watchers, journalized.project) &&
-      journalized.valid_watcher?(user) &&
-      !journalized.watched_by?(user)
+    journalized.journal_process_watchers(self)
   end
 
   def send_notification
-    if notify? &&
-        (
-          Setting.notified_events.include?('issue_updated') ||
-          (Setting.notified_events.include?('issue_note_added') && notes.present?) ||
-          (Setting.notified_events.include?('issue_status_updated') && new_status.present?) ||
-          (Setting.notified_events.include?('issue_assigned_to_updated') && detail_for_attribute('assigned_to_id').present?) ||
-          (Setting.notified_events.include?('issue_priority_updated') && new_value_for('priority_id').present?) ||
-          (Setting.notified_events.include?('issue_fixed_version_updated') && detail_for_attribute('fixed_version_id').present?) ||
-          (Setting.notified_events.include?('issue_attachment_added') && details.any? {|d| d.property == 'attachment' && d.value })
-        )
-      Mailer.deliver_issue_edit(self)
-    end
+    journalized.journal_notify(self)
   end
 
   def select_journal_visible_user(notified)
     if private_notes?
-      notified = notified.select {|user| user.allowed_to?(:view_private_notes, journalized.project)}
+      notified = notified.select {|user| journalized.journal_user_can_view_private_notes?(user)}
     end
     notified
   end
diff --git a/app/views/journals/_notes_form.html.erb b/app/views/journals/_notes_form.html.erb
index 4213d6613..1e44f0d84 100644
--- a/app/views/journals/_notes_form.html.erb
+++ b/app/views/journals/_notes_form.html.erb
@@ -18,4 +18,4 @@
     <p><%= submit_tag l(:button_save) %>
     <%= link_to l(:button_cancel), '#', :onclick => "$('#journal-#{@journal.id}-form').remove(); $('#journal-#{@journal.id}-notes').show(); return false;" %></p>
 <% end %>
-<%= wikitoolbar_for "journal_#{@journal.id}_notes", preview_issue_path(:project_id => @project, :issue_id => @journal.issue) %>
+<%= wikitoolbar_for "journal_#{@journal.id}_notes", preview_issue_path(:project_id => @project, :issue_id => @journal.journalized) %>
diff --git a/app/views/journals/index.builder b/app/views/journals/index.builder
index a7ddd71c4..a6d9fbb90 100644
--- a/app/views/journals/index.builder
+++ b/app/views/journals/index.builder
@@ -10,11 +10,11 @@ xml.feed "xmlns" => "http://www.w3.org/2005/Atom" do
   xml.updated((@journals.first ? @journals.first.event_datetime : Time.now).xmlschema)
   xml.author  {xml.name "#{Setting.app_title}"}
   @journals.each do |change|
-    issue = change.issue
+    journalized = change.journalized
     xml.entry do
-      xml.title   "#{issue.project.name} - #{issue.tracker.name} ##{issue.id}: #{issue.subject}"
-      xml.link    "rel" => "alternate", "href" => issue_url(issue)
-      xml.id      issue_url(issue, :journal_id => change)
+      xml.title   journalized.journal_event_title(change)
+      xml.link    "rel" => "alternate", "href" => issue_url(journalized)
+      xml.id      issue_url(journalized, :journal_id => change)
       xml.updated change.created_on.xmlschema
       xml.author do
         xml.name change.user.name
diff --git a/app/views/journals/update.js.erb b/app/views/journals/update.js.erb
index 2ab11cac9..230333821 100644
--- a/app/views/journals/update.js.erb
+++ b/app/views/journals/update.js.erb
@@ -2,9 +2,9 @@
   $("#change-<%= @journal.id %>").remove();
 <% else %>
   $("#change-<%= @journal.id %>").attr('class', '<%= @journal.css_classes %>');
-  $("#change-<%= @journal.id %> .journal-actions").html('<%= escape_javascript(render_journal_actions(@journal.issue, @journal, :reply_links => authorize_for('issues', 'edit'))) %>');
+  $("#change-<%= @journal.id %> .journal-actions").html('<%= escape_javascript(render_journal_actions(@journal.journalized, @journal, :reply_links => authorize_for('issues', 'edit'))) %>');
   $("#journal-<%= @journal.id %>-private_notes").replaceWith('<%= escape_javascript(render_private_notes_indicator(@journal)) %>');
-  $("#journal-<%= @journal.id %>-notes").replaceWith('<%= escape_javascript(render_notes(@journal.issue, @journal, :reply_links => authorize_for('issues', 'edit'))) %>');
+  $("#journal-<%= @journal.id %>-notes").replaceWith('<%= escape_javascript(render_notes(@journal.journalized, @journal, :reply_links => authorize_for('issues', 'edit'))) %>');
   $("#journal-<%= @journal.id %>-notes").show();
   $("#journal-<%= @journal.id %>-form").remove();
   var journal_header = $("#change-<%= @journal.id %>>div.note>h4.journal-header>.journal-info");
diff --git a/lib/plugins/acts_as_journalized/init.rb b/lib/plugins/acts_as_journalized/init.rb
new file mode 100644
index 000000000..bf0eb1891
--- /dev/null
+++ b/lib/plugins/acts_as_journalized/init.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+# Redmine - project management software
+# Copyright (C) 2006-  Jean-Philippe Lang
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+require_relative 'lib/acts_as_journalized'
+Rails.application.reloader.to_prepare do
+  ApplicationRecord.send(:include, Redmine::Acts::Journalized)
+end
diff --git a/lib/plugins/acts_as_journalized/lib/acts_as_journalized.rb b/lib/plugins/acts_as_journalized/lib/acts_as_journalized.rb
new file mode 100644
index 000000000..da11863c5
--- /dev/null
+++ b/lib/plugins/acts_as_journalized/lib/acts_as_journalized.rb
@@ -0,0 +1,138 @@
+# frozen_string_literal: true
+
+# Redmine - project management software
+# Copyright (C) 2006-  Jean-Philippe Lang
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+module Redmine
+  module Acts
+    module Journalized
+      def self.included(base)
+        base.extend ClassMethods
+      end
+
+      module ClassMethods
+        def acts_as_journalized(options = {})
+          class_attribute :journal_activity_type
+
+          has_many :journals, as: :journalized, dependent: :destroy, inverse_of: :journalized
+
+          Journal.register_journalized_type(self)
+          self.journal_activity_type = options[:activity_type]
+          Journal.register_activity_provider(self) if journal_activity_type.present?
+
+          include InstanceMethods
+        end
+
+        # Visibility
+        # Returns journalized records visible for the given user.
+        # Default implementation simply returns all records.
+        def journal_visible_scope(user = User.current, options = {})
+          all
+        end
+
+        def journal_notes_visibility_scope(scope, user, options = {})
+          scope
+        end
+
+        def journal_visibility_scope(scope)
+          scope
+        end
+
+        # scope contains journals of the current journalized class only
+        def journal_activity_scope(scope)
+          scope
+        end
+
+        def journal_activity_preload
+          []
+        end
+      end
+
+      module InstanceMethods
+        # Event API
+        def journal_event_title(journal)
+          "#{self.class.model_name.human} ##{id}"
+        end
+
+        def journal_event_type(journal)
+          'journal-update'
+        end
+
+        def journal_event_url(journal)
+          {}
+        end
+
+        # Notification API
+        def journal_notify(journal)
+          # no-op
+        end
+
+        # Watcher API
+        def journal_process_watchers(journal)
+          # no-op
+        end
+
+        # Journal detail tracking API
+        def journalized_attribute_names
+          []
+        end
+
+        # Recipient API
+        def journal_notified_users
+          respond_to?(:notified_users) ? notified_users : []
+        end
+
+        def journal_notified_watchers
+          respond_to?(:notified_watchers) ? notified_watchers : []
+        end
+
+        # Visibility API
+        def journal_visible?(user = User.current)
+          respond_to?(:visible?) ? visible?(user) : true
+        end
+
+        def journal_project
+          respond_to?(:project) ? project : nil
+        end
+
+        def journal_editable_by?(journal, user)
+          false
+        end
+
+        def journal_relation_visible?(detail, user)
+          true
+        end
+
+        def journal_user_can_view_private_notes?(user)
+          true
+        end
+
+        def journal_private_notes_allowed?(user)
+          false
+        end
+
+        def journal_valid_watcher?(user)
+          false
+        end
+
+        def journal_new_status(journal)
+          nil
+        end
+      end
+    end
+  end
+end
diff --git a/test/unit/changeset_test.rb b/test/unit/changeset_test.rb
index 7a814fe34..766a951a8 100644
--- a/test/unit/changeset_test.rb
+++ b/test/unit/changeset_test.rb
@@ -313,7 +313,7 @@ class ChangesetTest < ActiveSupport::TestCase
       end
       assert issue.reload.closed?
       journal = Journal.order(id: :desc).first
-      assert_equal issue, journal.issue
+      assert_equal issue, journal.journalized
       assert_include "Applied in changeset ecookbook:r12345.", journal.notes
     end
   end
diff --git a/test/unit/journal_test.rb b/test/unit/journal_test.rb
index 4f130990a..7c0583a33 100644
--- a/test/unit/journal_test.rb
+++ b/test/unit/journal_test.rb
@@ -26,7 +26,7 @@ class JournalTest < ActiveSupport::TestCase
   end
 
   def test_journalized_is_an_issue
-    issue = @journal.issue
+    issue = @journal.journalized
     assert_kind_of Issue, issue
     assert_equal 1, issue.id
   end
@@ -181,7 +181,7 @@ class JournalTest < ActiveSupport::TestCase
     # Anonymous user should see issues of public projects only
     journals = Journal.visible(User.anonymous).to_a
     assert journals.any?
-    assert_nil journals.detect {|journal| !journal.issue.project.is_public?}
+    assert_nil journals.detect {|journal| !journal.project.is_public?}
     # Anonymous user should not see issues without permission
     Role.anonymous.remove_permission!(:view_issues)
     journals = Journal.visible(User.anonymous).to_a
@@ -194,7 +194,7 @@ class JournalTest < ActiveSupport::TestCase
     # Non member user should see issues of public projects only
     journals = Journal.visible(user).to_a
     assert journals.any?
-    assert_nil journals.detect {|journal| !journal.issue.project.is_public?}
+    assert_nil journals.detect {|journal| !journal.project.is_public?}
     # Non member user should not see issues without permission
     Role.non_member.remove_permission!(:view_issues)
     user.reload
@@ -205,7 +205,7 @@ class JournalTest < ActiveSupport::TestCase
     user.reload
     journals = Journal.visible(user).to_a
     assert journals.any?
-    assert_nil journals.detect {|journal| journal.issue.project_id != 1}
+    assert_nil journals.detect {|journal| journal.journalized.project_id != 1}
   end
 
   def test_visible_scope_for_admin
@@ -215,7 +215,7 @@ class JournalTest < ActiveSupport::TestCase
     journals = Journal.visible(user).to_a
     assert journals.any?
     # Admin should see issues on private projects that admin does not belong to
-    assert journals.detect {|journal| !journal.issue.project.is_public?}
+    assert journals.detect {|journal| !journal.project.is_public?}
   end
 
   def test_preload_journals_details_custom_fields_should_set_custom_field_instance_variable
@@ -268,7 +268,7 @@ class JournalTest < ActiveSupport::TestCase
     visible_issue = Issue.generate!
     hidden_issue = Issue.generate!(:is_private => true)
 
-    journal = Journal.new
+    journal = Journal.new(journalized: issue)
     journal.details << JournalDetail.new(:property => 'relation', :prop_key => 'relates', :value => visible_issue.id)
     journal.details << JournalDetail.new(:property => 'relation', :prop_key => 'relates', :value => hidden_issue.id)
 
diff --git a/test/unit/mail_handler_test.rb b/test/unit/mail_handler_test.rb
index 24ec07f65..5f22d1d18 100644
--- a/test/unit/mail_handler_test.rb
+++ b/test/unit/mail_handler_test.rb
@@ -944,7 +944,7 @@ class MailHandlerTest < ActiveSupport::TestCase
     assert_equal Issue.find(2), journal.journalized
     assert_match /This is reply/, journal.notes
     assert_equal false, journal.private_notes
-    assert_equal 'Feature request', journal.issue.tracker.name
+    assert_equal 'Feature request', journal.journalized.tracker.name
   end
 
   def test_update_issue_should_accept_issue_id_after_space_inside_brackets
@@ -977,11 +977,11 @@ class MailHandlerTest < ActiveSupport::TestCase
                                                'start_date', 'due_date',
                                                'float field'])
     assert journal.is_a?(Journal)
-    issue = Issue.find(journal.issue.id)
+    issue = Issue.find(journal.journalized.id)
     assert_equal User.find_by_login('jsmith'), journal.user
     assert_equal Issue.find(2), journal.journalized
     assert_match /This is reply/, journal.notes
-    assert_equal 'Feature request', journal.issue.tracker.name
+    assert_equal 'Feature request', journal.journalized.tracker.name
     assert_equal IssueStatus.find_by_name("Resolved"), issue.status
     assert_equal '2010-01-01', issue.start_date.to_s
     assert_equal '2010-12-31', issue.due_date.to_s
@@ -1042,8 +1042,8 @@ class MailHandlerTest < ActiveSupport::TestCase
       )
     assert journal.is_a?(Journal)
     assert_match /This is reply/, journal.notes
-    assert_equal 'Feature request', journal.issue.tracker.name
-    assert_equal 'Normal', journal.issue.priority.name
+    assert_equal 'Feature request', journal.journalized.tracker.name
+    assert_equal 'Normal', journal.journalized.priority.name
   end
 
   def test_update_issue_should_add_cc_as_watchers
diff --git a/test/unit/mailer_test.rb b/test/unit/mailer_test.rb
index ab880ef45..272404626 100644
--- a/test/unit/mailer_test.rb
+++ b/test/unit/mailer_test.rb
@@ -362,7 +362,7 @@ class MailerTest < ActiveSupport::TestCase
 
   def test_issue_edit_message_id
     journal = Journal.find(3)
-    journal.issue = Issue.find(2)
+    journal.journalized = Issue.find(2)
 
     Mailer.deliver_issue_edit(journal)
     mail = last_email