RuntimeError when saveing HABTM

[jcoyne]

class TimeSpan < ActiveFedora::Base
  has_many :images, inverse_of: :created # predicate: ::RDF::DC.created
end
class Image < ActiveFedora::Base
   has_and_belongs_to_many :created, predicate: RDF::DC.created, class_name: 'TimeSpan'
end

Image.new(created: [TimeSpan.new])

causes:

RuntimeError: Unable to lookup the :predicate attribute for has_many :images on TimeSpan because Image specifies "class_name: 'ActiveFedora::Base'".  Either specify a specific class_name in Image or set :predicate in the has_many declaration on TimeSpan
    from /Users/justin/.rbenv/versions/2.2.1/lib/ruby/gems/2.2.0/bundler/gems/active_fedora-14566e3e435a/lib/active_fedora/associations/collection_association.rb:358:in `find_reflection_for_relation'

it does work if you set the predicate on has_many, but it seems that there's enough information here to not require that.