class ActiveModelSerializers::Adapter::JsonApi::Relationship

def as_json
  hash = {}
  hash[:data] = data_for(association) if association.include_data?
  links = links_for(association)
  hash[:links] = links if links.any?
  meta = meta_for(association)
  hash[:meta] = meta if meta
  hash[:meta] = {} if hash.empty?
  hash
end