class ActiveRecord::ConnectionAdapters::ReferenceDefinition

def initialize(
  name,
  polymorphic: false,
  index: true,
  foreign_key: false,
  type: :bigint,
  **options
)
  @name = name
  @polymorphic = polymorphic
  @index = index
  @foreign_key = foreign_key
  @type = type
  @options = options
  if polymorphic && foreign_key
    raise ArgumentError, "Cannot add a foreign key to a polymorphic relation"
  end
end