Deprecate public methods for removed collection size feature

app/models/concerns/hyrax/collection_behavior.rb

@@ -111,6 +111,17 @@ def collection_type_gid_document_field_name
       end
     end
 
+    # @deprecated to be removed in 4.0.0; this feature was replaced with a
+    #   hard-coded null implementation
+    # @return [Fixnum] 0
+    def bytes
+      Deprecation.warn("#bytes has been deprecated for removal in Hyrax 4.0.0; " \
+                       "The implementation of the indexed Collection size " \
+                       "feature extremely inefficient, so it has been removed. " \
+                       "This method now returns a hard-coded `0` for compatibility.")
+      0
+    end
+
     # @api public
     # Retrieve the permission template for this collection.
     # @return [Hyrax::PermissionTemplate]

app/presenters/hyrax/collection_presenter.rb

@@ -49,15 +49,32 @@ def terms_with_values
       self.class.terms.select { |t| self[t].present? }
     end
 
+    ##
+    # @param [Symbol] key
+    # @return [Object]
     def [](key)
       case key
+      when size
+        size
       when :total_items
         total_items
       else
         solr_document.send key
       end
     end
 
+    # @deprecated to be removed in 4.0.0; this feature was replaced with a
+    #   hard-coded null implementation
+    # @return [String] 'unknown'
+    def size
+      Deprecation.warn("#size has been deprecated for removal in Hyrax 4.0.0; " \
+                       "The implementation of the indexed Collection size " \
+                       "feature extremely inefficient, so it has been removed. " \
+                       "This method now returns a hard-coded `\"unknown\"` for " \
+                       "compatibility.")
+      'unknown'
+    end
+
     def total_items
       ActiveFedora::Base.where("member_of_collection_ids_ssim:#{id}").count
     end