use refinement

Author: Watson1978

lib/fluent/plugin/in_otlp.rb

@@ -4,8 +4,23 @@
 require "fluent/plugin/otlp/constant"
 require "fluent/plugin/otlp/request"
 require "fluent/plugin/otlp/response"
+require "fluent/plugin_helper/http_server"
 require "zlib"
 
+unless Fluent::PluginHelper::HttpServer::Request.method_defined?(:headers)
+  module Fluent::PluginHelper::HttpServer
+    module Extension
+      refine Request do
+        def headers
+          @request.headers
+        end
+      end
+    end
+  end
+
+  using Fluent::PluginHelper::HttpServer::Extension
+end
+
 module Fluent::Plugin
   class OtlpInput < Input
     Fluent::Plugin.register_input("otlp", self)