Fix camelcase directive kwargs

lib/graphql/stitching/composer.rb

@@ -468,8 +468,6 @@ def build_merged_directives(type_name, members_by_location, owner, field_name: n
           kwarg_values_by_name_location = directives_by_location.each_with_object({}) do |(location, directive), memo|
             directive.arguments.keyword_arguments.each do |key, value|
               key = key.to_s
-              next unless directive_class.arguments[key]
-
               memo[key] ||= {}
               memo[key][location] = value
             end

test/graphql/stitching/composer/merge_directive_test.rb

@@ -3,7 +3,6 @@
 require "test_helper"
 
 describe 'GraphQL::Stitching::Composer, merging directives' do
-
   def test_merges_directive_definitions
     a = %|
       """a"""
@@ -78,4 +77,25 @@ def test_omits_stitching_directives_and_includes_supergraph_directives
     assert_equal ["source"], supergraph.schema.query.get_field("testA").directives.map(&:graphql_name)
     assert_equal ["source"], supergraph.schema.query.get_field("testB").directives.map(&:graphql_name)
   end
+
+  def test_merges_camel_case_directive_values
+    a = %|
+      directive @fizzbuzz(sfooBar: String!) on OBJECT
+      type Test @fizzbuzz(sfooBar: "A") { field: String }
+      type Query { test: Test }
+    |
+
+    b = %|
+      directive @fizzbuzz(sfooBar: String!) on OBJECT
+      type Test @fizzbuzz(sfooBar: "B") { field: String }
+      type Query { test: Test }
+    |
+
+    supergraph = compose_definitions({ "a" => a, "b" => b }, {
+      directive_kwarg_merger: ->(str_by_location, _info) { str_by_location.values.join("/") }
+    })
+
+    directives = supergraph.schema.get_type("Test").directives
+    assert_equal "A/B", directives.first.arguments.keyword_arguments[:sfoo_bar]
+  end
 end