replace `is_project_milestone?` with `project_milestone?`

app/helpers/milestones_routing_helper.rb

@@ -2,7 +2,7 @@ module MilestonesRoutingHelper
   def milestone_path(milestone, *args)
     if milestone.is_group_milestone?
       group_milestone_path(milestone.group, milestone, *args)
-    elsif milestone.is_project_milestone?
+    elsif milestone.project_milestone?
       project_milestone_path(milestone.project, milestone, *args)
     end
   end
@@ -10,7 +10,7 @@ module MilestonesRoutingHelper
   def milestone_url(milestone, *args)
     if milestone.is_group_milestone?
       group_milestone_url(milestone.group, milestone, *args)
-    elsif milestone.is_project_milestone?
+    elsif milestone.project_milestone?
       project_milestone_url(milestone.project, milestone, *args)
     end
   end

app/models/concerns/milestoneish.rb

@@ -74,7 +74,7 @@ module Milestoneish
     false
   end
 
-  def is_project_milestone?
+  def project_milestone?
     false
   end
 

app/models/milestone.rb

@@ -211,7 +211,7 @@ class Milestone < ActiveRecord::Base
     group_id.present?
   end
 
-  def is_project_milestone?
+  def project_milestone?
     project_id.present?
   end
 

app/services/milestones/close_service.rb

 module Milestones
   class CloseService < Milestones::BaseService
     def execute(milestone)
-      if milestone.close && milestone.is_project_milestone?
+      if milestone.close && milestone.project_milestone?
         event_service.close_milestone(milestone, current_user)
       end
 

app/services/milestones/create_service.rb

@@ -3,7 +3,7 @@ module Milestones
     def execute
       milestone = parent.milestones.new(params)
 
-      if milestone.save && milestone.is_project_milestone?
+      if milestone.save && milestone.project_milestone?
         event_service.open_milestone(milestone, current_user)
       end
 

app/services/milestones/destroy_service.rb

 module Milestones
   class DestroyService < Milestones::BaseService
     def execute(milestone)
-      return unless milestone.is_project_milestone?
+      return unless milestone.project_milestone?
 
       Milestone.transaction do
         update_params = { milestone: nil }

app/services/milestones/reopen_service.rb

 module Milestones
   class ReopenService < Milestones::BaseService
     def execute(milestone)
-      if milestone.activate && milestone.is_project_milestone?
+      if milestone.activate && milestone.project_milestone?
         event_service.reopen_milestone(milestone, current_user)
       end