presto-iceberg/src/main/java/io/prestosql/plugin/iceberg/IcebergMetadata.java/IcebergMetadata/getColumnMetadatas
class IcebergMetadata:    private List<ColumnMetadata> getColumnMetadatas(org.apache.iceberg.Table table)
    {
        return table.schema().columns().stream()
                .map(column -> {
                    return ColumnMetadata.builder()
                            .setName(column.name())
                            .setType(toPrestoType(column.type(), typeManager))
                            .setComment(Optional.ofNullable(column.doc()))
                            .build();
                })
                .collect(toImmutableList());
    }