docs: @Handler
      @SuppressWarnings({ "PMD.AvoidInstantiatingObjectsInLoops",
          "PMD.AccessorClassGeneration", "PMD.AvoidDuplicateLiterals" })
      public void onStreamFile(StreamFile event)
              throws InterruptedException {
          if (Arrays.asList(event.options())
              .contains(StandardOpenOption.WRITE)) {
              throw new IllegalArgumentException(
                  "Cannot stream file opened for writing.");
          }
          for (IOSubchannel channel : event.channels(IOSubchannel.class)) {
              if (inputWriters.containsKey(channel)) {
                  channel.respond(new IOError(event,
                      new IllegalStateException("File is already open.")));
              } else {
                  new FileStreamer(event, channel);
              }
          }
      }