Items Builder: allow setting initial state on a group item (#261)

Signed-off-by: Jimmy Tanagra <jcode@tanagra.id.au>

lib/openhab/dsl/items/builder.rb

@@ -672,7 +672,6 @@ def #{m}(*args, groups: nil, **kwargs)  # def dimmer_item(*args, groups: nil, **
         # @param (see ItemBuilder#initialize)
         def initialize(*args, type: nil, function: nil, thing: nil, **kwargs)
           raise ArgumentError, "invalid function #{function}" if function && !function.match?(FUNCTION_REGEX)
-          raise ArgumentError, "state cannot be set on GroupItems" if kwargs[:state]
 
           super(type, *args, **kwargs)
           @function = function

spec/openhab/dsl/items/builder_spec.rb

@@ -534,6 +534,11 @@ def build_and_update(org_config, new_config, item_to_keep: :new_item, &block)
     expect(DateTimeItem1.state).to eq Time.parse("1970-01-01T00:00:00+00:00")
   end
 
+  it "sets initial state on a group item" do
+    items.build { group_item "GroupItem1", type: "Switch", state: ON }
+    expect(GroupItem1.state).to be ON
+  end
+
   describe "entity lookup" do
     it "can reference a group item directly" do
       items.build do