We were facing the same problem in our company. What we did to resolve this problem was to use the UrlEncoder to encode the cookie value before setting. This will encode all equals signs. And when retrieving the cookie we use UrlDecoder before using the value.
Both UrlEncoder and UrlDecoder can be found in the java.net package.
Making your instance variables public is a big no no in OO design. The whole point of using getters and setters is that when any business rules changes for that class in future versions, you can't change it in your class anymore. Changing it would break other people's code when they depend on that class.
Leaving it like you would now would definitely mean major point loss.
I definitely see some advantages to use Groovy in certain use cases. But what I wonder is how scalable is Groovy? Will it perform in big e-commerce sites just as good as in smaller ones? Can you name any success stories?