[#2180] Expose migrated PJs as legacy PJs in dossier API

app/serializers/dossier_serializer.rb

@@ -47,6 +47,11 @@ class DossierSerializer < ActiveModel::Serializer
     []
   end
 
+  def pieces_justificatives
+    ActiveModelSerializers::SerializableResource.new(object.pieces_justificatives).serializable_hash +
+      PiecesJustificativesService.serialize_champs_as_pjs(object)
+  end
+
   def email
     object.user&.email
   end

app/services/pieces_justificatives_service.rb

@@ -84,4 +84,15 @@ class PiecesJustificativesService
       }
     end
   end
+
+  def self.serialize_champs_as_pjs(dossier)
+    dossier.champs.select { |champ| champ.type_de_champ.old_pj }.map do |champ|
+      {
+        created_at: champ.created_at&.in_time_zone('UTC'),
+        type_de_piece_justificative_id: champ.type_de_champ.old_pj[:stable_id],
+        content_url: champ.for_api,
+        user: champ.dossier.user
+      }
+    end
+  end
 end