private Long snapshotIdOfTableRef(Table table, String ref) {
    if (ref == null) {
      ref = SnapshotRef.MAIN_BRANCH;
    }
    Snapshot snapshot = table.snapshot(ref);
    if (snapshot == null) {
      return null;
    }
    return snapshot.snapshotId();
  }
Descriptor for Mixed-Hive, Mixed-Iceberg, Iceberg format tables.
amoro-ams/src/main/java/org/apache/amoro/server/dashboard/MixedAndIcebergTableDescriptor.java