[tk-multi-publish2] Where do I add resolving logic for a custom key?

This is my publish yaml:

shot step

settings.tk-multi-publish2.nuke.shot_step:
collector: “{self}/collector.py:{config}/tk-multi-publish2/tk-nuke/basic/collector.py”
collector_settings:
Work Template: nuke_shot_work
publish_plugins:
- name: Publish to Shotgun
hook: “{self}/publish_file.py”
settings: {}
- name: Upload for review
hook: “{self}/upload_version.py”
settings: {}
- name: Begin file versioning
hook: “{engine}/tk-multi-publish2/basic/nuke_start_version_control.py”
settings: {}
- name: Publish to Shotgun
hook: “{self}/publish_file.py:{engine}/tk-multi-publish2/basic/nuke_publish_script.py”
settings:
Publish Template: nuke_shot_publish
- name: Submit for Review
hook: “{engine}/tk-multi-publish2/basic/submit_for_review.py”
settings: {}
- name: Publish and Generate Shotgun Version
hook: “{self}/publish_file.py:{config}/tk-multi-publish2/tk-nuke/basic/publish_version.py”
settings:
Shot Frames Publish Template: custom_shot_frames_output_publish
Shot Movie Publish Template: custom_shot_mov_output_publish
Shot Raw Movie Publish Template: custom_shot_raw_mov_output_publish
- name: Render Playable Media
hook: “{config}/tk-multi-publish2/render_playable_media.py”
settings: {}
post_phase: “{self}/post_phase.py:{config}/tk-multi-publish2/post_phase.py”
# - name: Update Flame Clip
# hook: “{engine}/tk-multi-publish2/basic/nuke_update_flame_clip.py”
# settings:
# Flame Clip Template: flame_shot_clip
help_url: *help_url
location: “@apps.tk-multi-publish2.location