Task_info:
 'TASK' 'INFO' name=ID ';'

TASK INFO explorer.exe;
TASK INFO winword.exe;
TASK INFO excel.exe;

In my JavaValidator.java:
@Check
public void checktask(Task_info xtask)
{
 Task_Checker tsk = new Task_Checker();
 tsk.check_dupe(xtask);
}

class Task_Checker {
 def check_dupe(Task_info xtask)
 {
  System.out.println("size is" + xtask.size); <-- I am always getting zero here. I was expecting 3 task names.
 }
}

class Task_Checker {
 def check_dupe(Task_info xtask)
 {
  val int iSize = xtask.size
  for (i:0..iSize-1)
  {
   for (j:i+1..iSize)
   {
    if (xtask.get(i).name.equals(xtask.get(j).name))
     error(duplicate task)
   }
  }
 }
}

Task_grammar:
 'TASK' (Task_define | Task_use)
;

Task_define:
 'INFO' taskname=ID ';'
;

Task_use:
  'USE' taskname=ID PRIORITY=INT (save = 'SAVE')? ';'
;

Model += Task_grammar*

Task_grammar:
'TASK' (defs+=Task_define | use+=Task_use)*
;

Task_define:
 'INFO' taskname=ID ';'
;

Task_use:
  'USE' taskname=ID PRIORITY=INT (save = 'SAVE')? ';'
;

	def void check(Task_grammar x)
	{
		var EList<Task_define> y = x.defs;
		System.out.println("TEST Size is " + y.size);
	}

Model += Task_grammar*

Model: tasks += Task_grammar*
;

taskname=ID 

TASKNAME: ID '.' ID ;

      composedCheck = "org.eclipse.xtext.validation.NamesAreUniqueValidator"