code: @Override
    public Map<String, Object> toMap() {
      Object fileObject = this.file;
      Map<String, Object> untypedParamWithPrimitiveTypes = super.toMap();
      untypedParamWithPrimitiveTypes.put("file", fileObject);
      return untypedParamWithPrimitiveTypes;
    }
docs: Returns untyped parameters for file creation. Map value for {@code "file"} is the same
  instance of value set in {@link Builder#setFile(File)} or
  {@link Builder#setFile(java.io.FileInputStream)}; the file is not transformed or serialized
  at this level.
  @return Untyped parameters containing file object set in the builder.