--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.compiler/share/classes/javax/lang/model/UnknownEntityException.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2009, 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;
+
+/**
+ * Superclass of exceptions which indicate that an unknown kind of
+ * entity was encountered.  This situation can occur if the language
+ * evolves and new kinds of constructs are introduced.  Subclasses of
+ * this exception may be thrown by visitors to indicate that the
+ * visitor was created for a prior version of the language.
+ *
+ * @apiNote A common superclass for exceptions specific to different
+ * kinds of unknown entities allows a single catch block to easily
+ * provide uniform handling of those related conditions.
+ *
+ * @author Joseph D. Darcy
+ * @see javax.lang.model.element.UnknownElementException
+ * @see javax.lang.model.element.UnknownAnnotationValueException
+ * @see javax.lang.model.type.UnknownTypeException
+ * @since 1.7
+ */
+public class UnknownEntityException extends RuntimeException {
+
+    private static final long serialVersionUID = 269L;
+
+    /**
+     * Creates a new {@code UnknownEntityException} with the specified
+     * detail message.
+     *
+     * @param message the detail message
+     */
+    protected UnknownEntityException(String message) {
+        super(message);
+    }
+}