Remove unnecessary key check when pass a document parameter.

lib/mongoid/criteria/queryable/pipeline.rb

@@ -82,15 +82,13 @@ def project(entry)
         # @return [ Pipeline ] The pipeline.
         #
         # @since 2.0.0
-        def unwind(field)
-          unless field.respond_to? :keys
-            normalized = field.to_s
+        def unwind(field_or_doc)
+          unless field_or_doc.respond_to? :keys
+            normalized = field_or_doc.to_s
             name = aliases[normalized] || normalized
             push("$unwind" => name.__mongo_expression__)
           else
-            permit_keys = ['path', 'includeArrayIndex', 'preserveNullAndEmptyArrays'].freeze
-            normalized = BSON::Document.new(field.select { |k| permit_keys.include?(k.to_s) })
-            push("$unwind" => normalized)
+            push("$unwind" => field_or_doc)
           end
         end
 

spec/mongoid/criteria/queryable/pipeline_spec.rb

@@ -197,17 +197,15 @@
       end
     end
 
-    context "when provided a hash value" do
-      context "unnecessary keys should be removed" do
-        before do
-          pipeline.unwind(path: "$foo", "includeArrayIndex" => "index", preserveNullAndEmptyArrays: true, foo: "bar")
-        end
+    context "when provided a hash" do
+      before do
+        pipeline.unwind(path: "$author", "includeArrayIndex" => "author_index", preserveNullAndEmptyArrays: true)
+      end
 
-        it "only reserve permit keys" do
-          expect(pipeline).to eq([
-            { "$unwind" => { "path" => "$foo", "includeArrayIndex" => "index", "preserveNullAndEmptyArrays" => true } }
-          ])
-        end
+      it "sets the hash" do
+        expect(pipeline).to eq([
+          { "$unwind" => { path: "$author", "includeArrayIndex" => "author_index", preserveNullAndEmptyArrays: true } }
+        ])
       end
     end
   end