apply_mappings

# File actionpack/lib/action_dispatch/http/content_security_policy.rb, line 297
      def apply_mappings(sources)
        sources.map do |source|
          case source
          when Symbol
            apply_mapping(source)
          when String, Proc
            source
          else
            raise ArgumentError, "Invalid content security policy source: #{source.inspect}"
          end
        end
      end