presto-iceberg/src/main/java/io/prestosql/plugin/iceberg/IcebergMetadata.java/IcebergMetadata/getColumnHandles
class IcebergMetadata:    @Override
    public Map<String, ColumnHandle> getColumnHandles(ConnectorSession session, ConnectorTableHandle tableHandle)
    {
        IcebergTableHandle table = (IcebergTableHandle) tableHandle;
        org.apache.iceberg.Table icebergTable = getIcebergTable(metastore, hdfsEnvironment, session, table.getSchemaTableName());
        return getColumns(icebergTable.schema(), typeManager).stream()
                .collect(toImmutableMap(IcebergColumnHandle::getName, identity()));
    }