JBI RowMapper impl with 0 rows

Question

We have implemented JDBI RowMapper and wanted to check what will be the behavior if lets say the query returns 0 rows. The documentation says: Row mappers are invoked once for each row in the result set So what will happen if there were 0 rows returned form the query. Will the map method inside RowMapper never be invoked. We are getting NPE and that seems to be the only explanation since the object that the impl of RowMapper returns is null.