[I] RecordBatchBuilder doesn't work with list of structs. [arrow]

[via GitHub]

fpacanowski opened a new issue, #44918:
URL: https://github.com/apache/arrow/issues/44918

   ### Describe the bug, including details regarding any error messages, 
version, and platform.
   
   `RecordBatchBuilder` doesn't seem to correctly handle a schema that contains 
a list of structs. Here's a minimal test case:
   ```ruby
   schema = Arrow::Schema.new(
     [
      Arrow::Field.new("structs", Arrow::ListDataType.new(
        Arrow::StructDataType.new([
          Arrow::Field.new("foo", :int64),
          Arrow::Field.new("bar", :int64)
        ])
      ))
    ]
   )
   
   table = Arrow::RecordBatchBuilder.build(schema, [
     { structs: [] },
     { structs: [] },
   ]).to_table
   
   assert_equal(2, table.n_rows)
   ```
   
   Table should have 2 rows, but it's empty (tested on HEAD).
   
   I've also checked that equivalent code in PyArrow works correctly (the table 
has two rows):
   ```python
   import pyarrow as pa
   import pyarrow.parquet as pq
   
   schema = pa.schema(
       [
           pa.field(
               "structs",
               pa.list_(
                   pa.struct([
                       pa.field("foo", pa.int64()),
                       pa.field("bar", pa.int64())
                   ])
               )
           )
       ]
   )
   
   data = [
       {"structs": []},
       {"structs": []}
   ]
   
   table = pa.Table.from_pylist(data, schema=schema)
   print(table.shape)
   
   pq.write_table(table, "file.parquet")
   ```
   
   Related bug report: https://github.com/apache/arrow/issues/44742.
   
   ### Component(s)
   
   Ruby


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