class Ransack::Context

def sortable_attributes_for(klass)

model that defines either one has a sort list of its own.
`ransortable_attributes` defaults to `ransackable_attributes`, so a 
def sortable_attributes_for(klass)
  allowlist(klass, :ransortable_attributes, :ransackable_attributes) do
    klass.authorizable_ransackable_attributes
  end
end