Variant: report that arrow-rs produces "bad" shredded variant #10306

Describe the bug

Related to

• GH-590: Allow VARIANT value to be omitted parquet-format#591

on apache/parquet-format#591 (comment), @HuaHuaY reports

I found that arrow-rs already allows to omit value array.

arrow-rs/parquet-variant-compute/src/variant_array.rs

Line 858 in 7616e10

fn try_from(inner_struct: &StructArray) -> Result<Self> {

Specifically, according to this report when a shredded variant value array contains only nulls, then the arrow-rs writer omits writing it. According to the discussion apache/parquet-format#591 the spac requires writiing a value field (even though there are examples that don't have the value field)

To Reproduce

No response

Expected behavior

Not sure

Additional context

No response