--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/share/classes/javax/lang/model/element/UnknownElementException.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,83 @@
+/*
+ * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package javax.lang.model.element;
+
+/**
+ * Indicates that an unknown kind of element was encountered.  This
+ * can occur if the language evolves and new kinds of elements are
+ * added to the {@code Element} hierarchy.  May be thrown by an
+ * {@linkplain ElementVisitor element visitor} to indicate that the
+ * visitor was created for a prior version of the language.
+ *
+ * @author Joseph D. Darcy
+ * @author Scott Seligman
+ * @author Peter von der Ahé
+ * @see ElementVisitor#visitUnknown
+ * @since 1.6
+ */
+public class UnknownElementException extends RuntimeException {
+
+    private static final long serialVersionUID = 269L;
+
+    private transient Element element;
+    private transient Object parameter;
+
+    /**
+     * Creates a new {@code UnknownElementException}.  The {@code p}
+     * parameter may be used to pass in an additional argument with
+     * information about the context in which the unknown element was
+     * encountered; for example, the visit methods of {@link
+     * ElementVisitor} may pass in their additional parameter.
+     *
+     * @param e the unknown element, may be {@code null}
+     * @param p an additional parameter, may be {@code null}
+     */
+    public UnknownElementException(Element e, Object p) {
+        super("Unknown element: " + e);
+        element = e;
+        this.parameter = p;
+    }
+
+    /**
+     * Returns the unknown element.
+     * The value may be unavailable if this exception has been
+     * serialized and then read back in.
+     *
+     * @return the unknown element, or {@code null} if unavailable
+     */
+    public Element getUnknownElement() {
+        return element;
+    }
+
+    /**
+     * Returns the additional argument.
+     *
+     * @return the additional argument
+     */
+    public Object getArgument() {
+        return parameter;
+    }
+}