Prevent `RequestEncoder#encode_params` to parse falsey params

When a `get` method called with `as: :json` and `params: nil` or
`params: false` (explicitly or implicitly)
`RequestEncoder#encode_params` converts it into a `null` or `false`
value which includes a unexpected `null=` or `false` query string into
request URL. From now on `RequestEncoder#encode_params` checks whether
`params` is nil or not otherwise returns.

Move down `nil` conversion guard


Update CHANGELOG.md

1 files changed, 14 insertions, 0 deletions

diff --git a/actionpack/test/controller/integration_test.rb b/actionpack/test/controller/integration_test.rb
index 41812a82e1..39ede1442a 100644
--- a/actionpack/test/controller/integration_test.rb
+++ b/actionpack/test/controller/integration_test.rb
@@ -1079,6 +1079,20 @@ class IntegrationRequestEncodersTest < ActionDispatch::IntegrationTest
     end
   end
 
+  def test_get_request_with_json_excludes_null_query_string
+    with_routing do |routes|
+      routes.draw do
+        ActiveSupport::Deprecation.silence do
+          get ":action" => FooController
+        end
+      end
+
+      get "/foos_json", as: :json
+
+      assert_equal "http://www.example.com/foos_json", request.url
+    end
+  end
+
   private
     def post_to_foos(as:)
       with_routing do |routes|