code: public static void validateNestedRepeatedType(Class<?> parameterType, Field field) {
      if (isCollectionOrArray(parameterType)) {
        throw new IllegalArgumentException(
            " Cannot marshal a nested collection or array field " + field.getName());
      }
    }
docs: A field of type Collection<Collection> cannot be marshalled into bigquery data format as
  parameterized types nested more than one level cannot be determined at runtime. So cannot be
  marshalled.