Semicolon required for certain generics declarations

 import java.util.concurrent.atomic.AtomicInteger

 public class ThreadId
 {
  // Atomic integer containing the next thread ID to be assigned
  private static final AtomicInteger nextId = new AtomicInteger(0)

  // Thread local variable containing each thread's ID
  private static final ThreadLocal<Integer> threadId = [
                  initialValue: { return nextId.getAndIncrement() }
                  ] as ThreadLocal<Integer>;
 // The Semi-colon at the end of the prior line seems to be required.


  // Returns the current thread's unique ID, assigning it if necessary
  public static int get()
  {
      System.out.println( "Thread ID: " + threadId.get());
      return threadId.get();
  }


  public static void main( String[] args )
  {
      1.upto(3) {
          Thread.start { new ThreadId().get(); }


      }
  }

 }