Add deprecation warning to unused method

lib/administrate.rb

@@ -20,4 +20,14 @@ def self.warn_of_deprecated_option(name)
       "if you think otherwise.",
     )
   end
+
+  def self.warn_of_deprecated_method(klass, method)
+    ActiveSupport::Deprecation.warn(
+      "The method #{klass}##{method} is deprecated. " +
+      "If you are seeing this message you are probably " +
+      "using a dashboard that depends explicitly on it. " +
+      "Please make sure you update it to a version that " +
+      "does not use a deprecated API"
+    )
+  end
 end

lib/administrate/base_dashboard.rb

@@ -94,6 +94,8 @@ def collection_includes
     end
 
     def item_includes
+      # Deprecated, internal usage has moved to #item_associations
+      Administrate.warn_of_deprecated_method(self.class, :item_includes)
       attribute_includes(show_page_attributes)
     end