[C++][Parquet] Null value in nested non-nullable columns fails to write when the parent is null #55124

auto type =
    ::arrow::struct_({::arrow::field("inner", ::arrow::int32(), /*nullable=*/false)});
auto values = ::arrow::ArrayFromJSON(type, R"([{"inner": 42}])");
auto indices = ::arrow::ArrayFromJSON(::arrow::int32(), "[0, null]");
ASSERT_OK_AND_ASSIGN(auto array, ::arrow::compute::Take(*values, *indices));

const auto& structs = checked_cast<const ::arrow::StructArray&>(*array);
ASSERT_EQ(structs.null_count(), 1);
ASSERT_EQ(structs.field(0)->null_count(), 1);
auto table = ::arrow::Table::Make(
    ::arrow::schema({::arrow::field("outer", type, /*nullable=*/true)}),
    {std::move(array)});
ASSERT_OK(table->ValidateFull());
CheckSimpleRoundtrip(table, /*row_group_size=*/2);

// cpp/src/parquet/column_writer.cc

......

  Status WriteArrow(const int16_t* def_levels, const int16_t* rep_levels,
                    int64_t num_levels, const ::arrow::Array& leaf_array,
                    ArrowWriteContext* ctx, bool leaf_field_nullable) override {
    BEGIN_PARQUET_CATCH_EXCEPTIONS
    // Leaf nulls are canonical when there is only a single null element after a list
    // and it is at the leaf.
    bool single_nullable_element =
        (level_info_.def_level == level_info_.repeated_ancestor_def_level + 1) &&
        leaf_field_nullable;
    if (!leaf_field_nullable && leaf_array.null_count() != 0) {
      return Status::Invalid("Column '", descr_->name(),
                             "' is declared non-nullable but contains nulls");
    }