app/serializers/pens_micro_cluster_serializer.rb
class PensMicroClusterSerializer
include JSONAPI::Serializer
has_many :collected_pens
belongs_to :model_variant,
id_method_name: :pens_model_variant_id,
serializer: PensModelVariantSerializer
attribute :simplified_brand
attribute :simplified_model
attribute :simplified_color
attribute :simplified_material
attribute :simplified_trim_color
attribute :simplified_filling_system
end