https://understanddrupal.com/lessons/how-debug-drupal-migrations-part-2/
also install migrate_sandbox module
field_tags:
- plugin: skip_on_empty
source: src_fruit_list
method: process
message: 'No fruit_list listed.'
- plugin: debug
label: 'Step 1: Value received from the source plugin: '
- plugin: explode
delimiter: ','
- plugin: debug
label: 'Step 2: Exploded taxonomy term names '
multiple: true
- plugin: callback
callable: trim
- plugin: debug
label: 'Step 3: Trimmed taxonomy term names '
- plugin: entity_generate
entity_type: taxonomy_term
value_key: name
bundle_key: vid
bundle: tags
- plugin: debug
label: 'Step 4: Generated taxonomy term IDs '