lib/opentelemetry/context/propagation/rack_env_getter.rb in opentelemetry-api-1.2.1 vs lib/opentelemetry/context/propagation/rack_env_getter.rb in opentelemetry-api-1.2.2

@@ -30,10 +30,11 @@
         end
 
         private
 
         def to_rack_key(key)
-          ret = 'HTTP_' + key # rubocop:disable Style/StringConcatenation
+          # Use + for mutable string interpolation in pre-Ruby 3.0.
+          ret = +"HTTP_#{key}"
           ret.tr!('-', '_')
           ret.upcase!
           ret
         end