Required as a witness do i have to go to court?

You're right. In that little blurp it doesn't mention at all that it is mandatory that you be there. But, go ahead and blow it off. Contempt of court will follow with a warrant for your arrest and you will be put in jail until you do make yourself available to testify. No big deal, don't worry about it. See that word "required?" What do you suppose that means?