@Override
    public int[] toTopLevelIndexes() {
      if (isNested()) {
        throw new IllegalStateException(
            "Cannot convert a nested projection to a top level projection");
      }
      return Arrays.stream(projection).mapToInt(arr -> arr[0]).toArray();
    }
Create a {@link Projection} of a field range.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/util/Projection.java