--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.compiler/share/classes/javax/lang/model/util/AbstractElementVisitor6.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2005, 2017, Oracle and/or its affiliates. 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package javax.lang.model.util;
+
+import javax.annotation.processing.SupportedSourceVersion;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.*;
+import static javax.lang.model.SourceVersion.*;
+
+
+/**
+ * A skeletal visitor of program elements with default behavior
+ * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}
+ * source version.
+ *
+ * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
+ * implemented by this class may have methods added to it in the
+ * future to accommodate new, currently unknown, language structures
+ * added to future versions of the Java&trade; programming language.
+ * Therefore, methods whose names begin with {@code "visit"} may be
+ * added to this class in the future; to avoid incompatibilities,
+ * classes which extend this class should not declare any instance
+ * methods with names beginning with {@code "visit"}.
+ *
+ * <p>When such a new visit method is added, the default
+ * implementation in this class will be to call the {@link
+ * #visitUnknown visitUnknown} method.  A new abstract element visitor
+ * class will also be introduced to correspond to the new language
+ * level; this visitor will have different default behavior for the
+ * visit method in question.  When the new visitor is introduced, all
+ * or portions of this visitor may be deprecated.
+ *
+ * @param <R> the return type of this visitor's methods.  Use {@link
+ *            Void} for visitors that do not need to return results.
+ * @param <P> the type of the additional parameter to this visitor's
+ *            methods.  Use {@code Void} for visitors that do not need an
+ *            additional parameter.
+ *
+ * @author Joseph D. Darcy
+ * @author Scott Seligman
+ * @author Peter von der Ah&eacute;
+ *
+ * @see AbstractElementVisitor7
+ * @see AbstractElementVisitor8
+ * @see AbstractElementVisitor9
+ * @since 1.6
+ */
+@SupportedSourceVersion(RELEASE_6)
+public abstract class AbstractElementVisitor6<R, P> implements ElementVisitor<R, P> {
+    /**
+     * Constructor for concrete subclasses to call.
+     * @deprecated Release 6 is obsolete; update to a visitor for a newer
+     * release level.
+     */
+    @Deprecated
+    protected AbstractElementVisitor6(){}
+
+    /**
+     * Visits any program element as if by passing itself to that
+     * element's {@link Element#accept accept} method.  The invocation
+     * {@code v.visit(elem, p)} is equivalent to {@code elem.accept(v,
+     * p)}.
+     *
+     * @param e  the element to visit
+     * @param p  a visitor-specified parameter
+     * @return a visitor-specified result
+     */
+    public final R visit(Element e, P p) {
+        return e.accept(this, p);
+    }
+
+    /**
+     * Visits any program element as if by passing itself to that
+     * element's {@link Element#accept accept} method and passing
+     * {@code null} for the additional parameter.  The invocation
+     * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
+     * null)}.
+     *
+     * @param e  the element to visit
+     * @return a visitor-specified result
+     */
+    public final R visit(Element e) {
+        return e.accept(this, null);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @implSpec The default implementation of this method in
+     * {@code AbstractElementVisitor6} will always throw
+     * {@code new UnknownElementException(e, p)}.
+     * This behavior is not required of a subclass.
+     *
+     * @param e {@inheritDoc}
+     * @param p {@inheritDoc}
+     * @return a visitor-specified result
+     * @throws UnknownElementException
+     *          a visitor implementation may optionally throw this exception
+     */
+    @Override
+    public R visitUnknown(Element e, P p) {
+        throw new UnknownElementException(e, p);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @implSpec Visits a {@code ModuleElement} by calling {@code
+     * visitUnknown}.
+     *
+     * @param e  {@inheritDoc}
+     * @param p  {@inheritDoc}
+     * @return the result of {@code visitUnknown}
+     *
+     * @since 9
+     * @spec JPMS
+     */
+    @Override
+    public R visitModule(ModuleElement e, P p) {
+        // Use implementation from interface default method
+        return ElementVisitor.super.visitModule(e, p);
+    }
+}