skip_on_empty Read more about skip_on_empty Skips processing the current row when the input value is empty.
skip_row_if_not_set Read more about skip_row_if_not_set Skips processing the current row when a source value is not set.
make_unique_entity_field Read more about make_unique_entity_field Ensures the source value is made unique against an entity field.
migration_lookup Read more about migration_lookup Looks up the value of a property based on a previous migration.