Empty snapshot ID should be `Null` instead of `-1`

[Fokko]

This is an old bug from Java. Where the Snapshot was set to -1 instead of None:

iceberg-rust/crates/iceberg/src/spec/table_metadata.rs

Line 44 in aba6209

pub(crate) static EMPTY_SNAPSHOT_ID: i64 = -1;

From Java 1.5 and later this is fixed. For older version of Java, the current-snapshot-id is required. We solved this by setting a flag: apache/iceberg-python#473

[s-akhtar-baig]

@Fokko, can you please assign this to me? Thanks!

[Fokko]

@s-akhtar-baig With pleasure 🙌

[gupteaj]

@Fokko , @liurenjie1024
what changes are we looking for ?
Since rust is using option to hold snapshot id internally, but writing as -1 for V2 manifest files.
Does it need similar changes ( some variable ) as iceberg-python or empty snapshot id as -1 looks valid for rust.

[liurenjie1024]

I took a look the code and found that maybe we don't need to change anything since we already handled this case:

iceberg-rust/crates/iceberg/src/spec/table_metadata.rs

Line 678 in 6f85456

current_snapshot_id: if let &Some(id) = &value.current_snapshot_id {

But it would be better to add some tests for it.

[github-actions]

This issue has been automatically marked as stale because it has been open for 180 days with no activity. It will be closed in next 14 days if no further activity occurs. To permanently prevent this issue from being considered stale, add the label 'not-stale', but commenting on the issue is preferred when possible.

[liurenjie1024]

A bug to fix.