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diff --git a/javax/lang/model/element/ElementVisitor.java b/javax/lang/model/element/ElementVisitor.java
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+/* ElementVisitor.java -- A visitor of program elements.
+   Copyright (C) 2012  Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package javax.lang.model.element;
+
+/**
+ * <p>A visitor for program elements.  This is used when the specific
+ * type of element is not known at compile time.  A visitor instance
+ * is passed to the {@link Element#accept(ElementVisitor,P)} method of
+ * the element, which then calls the specific {@code visitN} method
+ * appropriate to that specific element.</p>
+ * <p>The additional parameter supplied to visitor methods may or
+ * may not be optional, and so the class is free to throw a
+ * {@code NullPointerException} if {@code null} is passed as the
+ * additional parameter.</p>
+ * <p>As this interface may be extended to accomodate future language
+ * versions, implementators are encouraged to extend one of the
+ * appropriate abstract classes rather than implementating this
+ * interface.  However, this interface should be used as the type
+ * for parameters and return values.</p>
+ *
+ * @param R the return type of the visitor's methods.  {@code Void}
+ *          can be used where there is no return value.
+ * @param P the type of the additional parameter supplied to the visitor's
+ *           methods.
+ *
+ * @since 1.6
+ */
+public interface ElementVisitor<R,P>
+{
+
+  /**
+   * A convenience method for use when there is no additional
+   * parameter to pass.  This is equivalent to {@code #visit(e, null)}.
+   *
+   * @param element the element to visit.
+   * @return the return value specific to the visitor.
+   */
+  R visit(Element element);
+
+  /**
+   * Visits an element.
+   *
+   * @param element the element to visit.
+   * @param param the additional parameter, specific to the visitor.
+   *        May be {@code null} if permitted by the visitor.
+   */
+  R visit(Element element, P param);
+
+  /**
+   * Visits a type element.
+   *
+   * @param element the type element to visit.
+   * @param param the additional parameter, specific to the visitor.
+   *        May be {@code null} if permitted by the visitor.
+   */
+  R visitType(TypeElement element, P param);
+
+  /**
+   * Visits an unknown element.  This method is called if
+   * a new type of element is added to the hierarchy
+   * which isn't yet handled by the visitor.
+   *
+   * @param element the element to visit.
+   * @param param the additional parameter, specific to the visitor.
+   *        May be {@code null} if permitted by the visitor.
+   * @return the return value specific to the visitor.
+   */
+  R visitUnknown(Element element, P param);
+
+}