def check_protected(specs)
      protected = []
      specs.each do |spec|
        msg = Wagons.find(spec.name).protect?
        protected << msg if msg.is_a?(String)
      end
      protected.join("\n").presence
    end
def check_protected(specs)
      protected = []
      specs.each do |spec|
        msg = Wagons.find(spec.name).protect?
        protected << msg if msg.is_a?(String)
      end
      protected.join("\n").presence
    end
Checks if the wagons for given gem specifications are protected.
 Returns nil if everything is fine or a string with error messages.