Trim WebHookUserSerializer.

spec/serializers/web_hook_user_serializer_spec.rb

@@ -18,4 +18,21 @@ RSpec.describe WebHookUserSerializer do
     expect(payload[:email]).to eq(user.email)
     expect(payload[:external_id]).to eq('12345')
   end
+
+  it 'should only include the required keys' do
+    count = serializer.as_json.keys.count
+    difference = count - 42
+
+    expect(difference).to eq(0), lambda {
+      message = ""
+
+      if difference < 0
+        message << "#{difference * -1} key(s) have been removed from this serializer."
+      else
+        message << "#{difference} key(s) have been added to this serializer."
+      end
+
+      message << "\nPlease verify if those key(s) are required as part of the web hook's payload."
+    }
+  end
 end