add rubocop

Author: Watson1978

.rubocop.yml

@@ -0,0 +1,31 @@
+inherit_from: .rubocop_todo.yml
+
+AllCops:
+  TargetRubyVersion: 3.1
+  Exclude:
+    - 'lib/opentelemetry/**/*.rb'
+
+Layout/LineLength:
+  Max: 140
+
+Lint/UnusedMethodArgument:
+  Enabled: false
+
+Metrics:
+  Enabled: false
+
+Style/Copyright:
+  Enabled: false
+
+Style/ClassAndModuleChildren:
+  Enabled: false
+
+Style/StringHashKeys:
+  Enabled: false
+
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
+
+Style/RequireOrder:
+  Enabled: true
+

.rubocop_todo.yml

@@ -0,0 +1,18 @@
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2025-04-04 09:06:04 UTC using RuboCop version 1.75.2.
+# The point is for the user to remove these configuration records
+# one by one as the offenses are removed from the code base.
+# Note that changes in the inspected code, or installation of new
+# versions of RuboCop, may require this file to be generated again.
+
+# Offense count: 10
+# Configuration parameters: AllowedConstants.
+Style/Documentation:
+  Exclude:
+    - 'spec/**/*'
+    - 'test/**/*'
+    - 'lib/fluent/plugin/in_otlp.rb'
+    - 'lib/fluent/plugin/otlp/request.rb'
+    - 'lib/fluent/plugin/otlp/response.rb'
+    - 'lib/fluent/plugin/out_otlp.rb'

Gemfile

@@ -9,3 +9,5 @@ gem "irb"
 gem "rake", "~> 13.0"
 
 gem "test-unit", "~> 3.0"
+
+gem "rubocop"