Stop CSVBulkLoader from adding blank records from $relationCallbacks

<%- if @topic_view.topic.tags.present? %>
<%= t 'js.tagging.tags' %>: <%- @topic_view.topic.tags.each do |t| %> <%= t %> <%- end %>
<% end %>

I have a custom CSVBulkLoader with a simple $relationCallbacks array setup to avoid duplicates on a related model… Is there a way to also avoid creating a record if the values coming from the CSV is empty? Maybe make some relationship fields required?