appease Rubocop

* Layout/HeredocIndentation: Use 2 spaces for indentation in a
  heredoc.
* Style/StringLiterals: Prefer single-quoted strings when you don't
  need string interpolation or special symbols.

* Style/StringConcatenation: Prefer string interpolation to string
  concatenation.
  - ... except we don't want *interpolation*; we want to join pathname
  components with the correct separator for the operating system. So
  we'll use Pathname.join explicitly instead of Pathname's :+ operator
  so Rubocop doesn't think we're concatonating strings.

Author: robbkidd

semantic_conventions/Rakefile

@@ -1,21 +1,21 @@
 # frozen_string_literal: true
 
 COPYRIGHT_NOTICE = <<~COPYRIGHT_NOTICE
-# Copyright The OpenTelemetry Authors
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-# SPDX-License-Identifier: Apache-2.0
+  # Copyright The OpenTelemetry Authors
+  #
+  # Licensed under the Apache License, Version 2.0 (the "License");
+  # you may not use this file except in compliance with the License.
+  # You may obtain a copy of the License at
+  #
+  #     http://www.apache.org/licenses/LICENSE-2.0
+  #
+  # Unless required by applicable law or agreed to in writing, software
+  # distributed under the License is distributed on an "AS IS" BASIS,
+  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  # See the License for the specific language governing permissions and
+  # limitations under the License.
+  #
+  # SPDX-License-Identifier: Apache-2.0
 COPYRIGHT_NOTICE
 
 require 'bundler/gem_tasks'
@@ -91,24 +91,24 @@ task generate_require_rollups: %i[generate_semconv] do
   puts "\n+++ Generating rollup/barrel files for semconv namespaces.\n"
 
   Rake::FileList[  # find all the generated semconv files
-    semconv_output_dir + "**" + "attributes.rb",
-    semconv_output_dir + "**" + "metrics.rb",
+    semconv_output_dir.join('**', 'attributes.rb'),
+    semconv_output_dir.join('**', 'metrics.rb'),
   ]
-    .pathmap("%d") # turn the list into the parent directories (root_namespaces)
+    .pathmap('%d') # turn the list into the parent directories (root_namespaces)
     .uniq          # remove duplicates
     .each do |namespace_dir| # in each directory, write out a file to require the generated signal names
       directory = Pathname.new(namespace_dir)
       rollup_filename = directory.dirname + "#{directory.basename}.rb"
-      File.open(rollup_filename, "w") do |rollup|
+      File.open(rollup_filename, 'w') do |rollup|
         rollup << <<~FILE_HEADER
           # frozen_string_literal: true
 
           #{COPYRIGHT_NOTICE}
           # This file was autogenerated. Do not edit it by hand.
 
         FILE_HEADER
-        rollup << "require_relative './#{directory.basename}/attributes.rb'\n" if File.exist?(directory + "attributes.rb")
-        rollup << "require_relative './#{directory.basename}/metrics.rb'\n" if File.exist?(directory + "metrics.rb")
+        rollup << "require_relative './#{directory.basename}/attributes.rb'\n" if File.exist?(directory.join('attributes.rb'))
+        rollup << "require_relative './#{directory.basename}/metrics.rb'\n" if File.exist?(directory.join('metrics.rb'))
       end
       puts "✅ Generated file \"#{rollup_filename}\""
     end