# File lib/bundler/source/rubygems.rb, line 276
      def dependency_names_to_double_check
        names = []
        remote_specs.each do |spec|
          case spec
          when EndpointSpecification, Gem::Specification, StubSpecification, LazySpecification
            names.concat(spec.runtime_dependencies)
          when RemoteSpecification # from the full index
            return nil
          else
            raise "unhandled spec type (#{spec.inspect})"
          end
        end
        names.map!(&:name) if names
        names
      end