public static void writeFiles(
    @NotNull IonWriter writer,
    @NotNull String fieldName,
    @NotNull Collection<File> files
  ) throws IOException {
    writeCollection(writer, fieldName, files, it ->
      writer.writeString(it.getPath())
    );
  }
public static void writeFiles(
    @NotNull IonWriter writer,
    @NotNull String fieldName,
    @NotNull Collection<File> files
  )