Question about request header configuration with initializer

Hello! I've attempted to set a header with the initializer:

# config/initializers/graphiql.rb
GraphiQL::Rails.config.headers["Authorization"] = -> (_context) { "here" }

My graphql endpoint looks like this:

# app/controllers/application_controller.rb
# omitting the rest of the file...
  def graphql
    puts "*"*50
    puts request.headers["Authorization"]
    puts "*"*50
  end

Server log when sending the request via GraphiQL:

Started POST "/graphql" for ::1 at 2020-03-31 15:46:13 -0700
Processing by ApplicationController#graphql as */*
  Parameters: {"query"=>"", "variables"=>"null", "operationName"=>nil, "application"=>{"query"=>"", "variables"=>"null", "operationName"=>nil}}
**************************************************

**************************************************
No template found for ApplicationController#graphql, rendering head :no_content

Do I need to invoke the config? Something else? The header is nil. This is a new Rails app with the following versions: Rails: 6.0.2.2 Ruby: 2.7.0 graphiql-rails: 1.7

rmosolgo / graphiql-rails

Question about request header configuration with initializer #82