Minor tweaks to get exec.connected working

java/core.worker/src/main/java/base/work/Listen.java

@@ -106,7 +106,5 @@ public abstract class Listen<E> extends Work implements Listener<E> {
         }
     }
 
-    public void input(E element) {
-        System.err.println(element);
-    }
+    public abstract void input(E element);
 }

java/core.worker/src/test/java/worker/dummy/DummyListen.java

@@ -23,4 +23,10 @@ public class DummyListen<T> extends Listen<T> {
     public void input(byte[] input) {
         System.out.println("#" + id + ", input = " + new String(input).trim());
     }
+
+	@Override
+	public void input(T element) {
+		// TODO Auto-generated method stub
+		
+	}
 }