Remove 'Adapter' suffix from adapters since they are in Adapter:: namespace

lib/active_model/serializer/adapter/json.rb

@@ -1,7 +1,7 @@
 module ActiveModel
   class Serializer
     class Adapter
-      class JsonAdapter < Adapter
+      class Json < Adapter
         def serializable_hash(options = {})
           serializer.attributes.each_with_object({}) do |(attr, value), h|
             h[attr] = value

lib/active_model/serializer/adapter/json_api.rb

@@ -1,7 +1,7 @@
 module ActiveModel
   class Serializer
     class Adapter
-      class JsonApiAdapter < Adapter
+      class JsonApi < Adapter
         def serializable_hash(options = {})
           @hash = serializer.attributes
 

lib/active_model/serializer/adapter/null.rb

@@ -1,7 +1,7 @@
 module ActiveModel
   class Serializer
     class Adapter
-      class NullAdapter < Adapter
+      class Null < Adapter
         def serializable_hash(options = {})
           {}
         end