allow empty groups in type form configuration

app/models/type/attribute_groups.rb

@@ -92,7 +92,6 @@ module Type::AttributeGroups
     groups.each do |_, attributes|
       attributes.select! { |attribute| valid_keys.include? attribute }
     end
-    groups.select! { |_,attributes| attributes.any? }
 
     groups.presence || default_attribute_groups
   end
@@ -163,7 +162,7 @@ module Type::AttributeGroups
 
   def validate_attribute_group_names
     seen = Set.new
-    attribute_groups.each do |group_key,_|
+    attribute_groups.each do |group_key, _|
       errors.add(:attribute_groups, :group_without_name) unless group_key.present?
       errors.add(:attribute_groups, :duplicate_group, group: group_key) if seen.add?(group_key).nil?
     end

frontend/app/components/types/form-configuration/types-form-configuration.controller.ts

@@ -167,9 +167,7 @@ function typesFormConfigurationCtrl(
         }
       });
 
-      if (attrKeys.length > 0) {
-        newAttrGroups.push([groupKey, attrKeys]);
-      }
+      newAttrGroups.push([groupKey, attrKeys]);
     });
 
 

spec/models/type/attribute_groups_spec.rb

@@ -1,4 +1,5 @@
 #-- encoding: UTF-8
+
 #-- copyright
 # OpenProject is a project management system.
 # Copyright (C) 2012-2017 the OpenProject Foundation (OPF)
@@ -49,11 +50,10 @@ describe ::Type, type: :model do
       expect(type.attribute_groups).to eq [['foo', ['date']]]
     end
 
-    it 'removes groups without attributes' do
+    it 'keeps groups without attributes' do
       type.attribute_groups = [['foo', []], ['bar', ['date']]]
-      expect(type.attribute_groups).to eq [['bar', ['date']]]
+      expect(type.attribute_groups).to eq [['foo', []], ['bar', ['date']]]
     end
-
   end
 
   describe '#default_attribute_groups' do
@@ -167,15 +167,15 @@ describe ::Type, type: :model do
   end
 
   describe 'custom fields' do
-    let!(:custom_field) {
+    let!(:custom_field) do
       FactoryGirl.create(
         :work_package_custom_field,
-        field_format: 'string',
+        field_format: 'string'
       )
-    }
-    let(:cf_identifier) {
+    end
+    let(:cf_identifier) do
       :"custom_field_#{custom_field.id}"
-    }
+    end
 
     it 'can be put into attribute groups' do
       # Is in inactive group