Could not create a solr index for custom table

Currently apachesolr module only support the drupal entity . It would be greatly helpful if there were support for custom tables as well.
I made alterations to enable this support.

apachesolr_index_entity_to_documents($item, $env_id)
apachesolr_convert_entity_to_documents($entity, $entity_type, $env_id) and
apachesolr_index_entities_document($row, $entity_type, $env_id) in file apachesolr.index.inc

Changes made are in the attached patch.