Builds a <fd:submit> widget. A submit is an action that
terminates the current form. It can either require the form to be valid
(in which case it will be redisplayed if not valid) or terminate it without
validation (e.g. a "cancel" button).
The "validate" attribute can have the value true or
false and determines if the form is to be validated
(defaults to true).
version: $Id: SubmitDefinitionBuilder.java 517843 2007-03-13 20:09:32Z vgritsenko $