use public API to fetch the parameter filter

now the parameter filter doesn't need to know about the env hash in
these two methds.

1 files changed, 2 insertions, 2 deletions

diff --git a/actionpack/lib/action_dispatch/http/filter_parameters.rb b/actionpack/lib/action_dispatch/http/filter_parameters.rb
index 3170389b36..e70e90018c 100644
--- a/actionpack/lib/action_dispatch/http/filter_parameters.rb
+++ b/actionpack/lib/action_dispatch/http/filter_parameters.rb
@@ -50,13 +50,13 @@ module ActionDispatch
     protected
 
       def parameter_filter
-        parameter_filter_for @env.fetch("action_dispatch.parameter_filter") {
+        parameter_filter_for get_header("action_dispatch.parameter_filter") {
           return NULL_PARAM_FILTER
         }
       end
 
       def env_filter
-        user_key = @env.fetch("action_dispatch.parameter_filter") {
+        user_key = get_header("action_dispatch.parameter_filter") {
           return NULL_ENV_FILTER
         }
         parameter_filter_for(Array(user_key) + ENV_MATCH)