public Long getSnapshotId() {
    return snapshotId;
  }
Entry of Iceberg ContentFile, include status, ContentFile, snapshotId and sequenceNumber. If the
actual sequenceNumber in manifest file is null, it will be inherited from metadata, and it may be
null for DELETED entries with iceberg version < 1.0.0.
amoro-format-iceberg/src/main/java/org/apache/amoro/IcebergFileEntry.java