hcrosse opened a new pull request, #723:
URL: https://github.com/apache/arrow-go/pull/723

   ### Rationale
   
   The Parquet spec says the root of the schema doesn't have a 
`repetition_type`. arrow-go writes `REPEATED` for the root `SchemaElement` in 
the Thrift footer, which breaks interop with consumers like Snowflake. #722 has 
the full writeup and cross-implementation comparison.
   
   ### What changes are included in this PR?
   
   `ToThrift()` now nils out `RepetitionType` on the root element before 
returning, stripping it from the serialized output. This matches how 
parquet-java and arrow-rs handle the root.
   
   The in-memory representation and `WithRootRepetition` API are unaffected. 
`FromParquet` already tolerates a nil root repetition type 
([schema.go#L78-L79](https://github.com/apache/arrow-go/blob/main/parquet/schema/schema.go#L78-L79)),
 so this is backwards-compatible for both readers and writers.
   
   ### Are these changes tested?
   
   Updated the existing `TestNestedExample` and added 
`TestToThriftRootRepetitionStripped` which checks that the root's 
`repetition_type` is stripped for all three repetition variants and that 
non-root elements keep theirs.
   
   Closes #722


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