Added the easy to add interfaces and implementations for java.util.concurrent to pave the way for future expansion of avians java.util.concurrent classpath implementation.

classpath/java/util/concurrent/RejectedExecutionException.java

@@ -0,0 +1,31 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util.concurrent;
+
+public class RejectedExecutionException extends RuntimeException {
+  private static final long serialVersionUID = -375805702767069545L;
+  
+  public RejectedExecutionException() {
+    super();
+  }
+  
+  public RejectedExecutionException(String message) {
+    super(message);
+  }
+  
+  public RejectedExecutionException(String message, Throwable cause) {
+    super(message, cause);
+  }
+  
+  public RejectedExecutionException(Throwable cause) {
+    super(cause);
+  }
+}