diff --git a/java/lang/ClassNotFoundException.java b/java/lang/ClassNotFoundException.java
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+/*
+ * Copyright (c) 1995, 2004, 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 java.lang;
+
+/**
+ * Thrown when an application tries to load in a class through its
+ * string name using:
+ * <ul>
+ * <li>The <code>forName</code> method in class <code>Class</code>.
+ * <li>The <code>findSystemClass</code> method in class
+ *     <code>ClassLoader</code> .
+ * <li>The <code>loadClass</code> method in class <code>ClassLoader</code>.
+ * </ul>
+ * <p>
+ * but no definition for the class with the specified name could be found.
+ *
+ * <p>As of release 1.4, this exception has been retrofitted to conform to
+ * the general purpose exception-chaining mechanism.  The "optional exception
+ * that was raised while loading the class" that may be provided at
+ * construction time and accessed via the {@link #getException()} method is
+ * now known as the <i>cause</i>, and may be accessed via the {@link
+ * Throwable#getCause()} method, as well as the aforementioned "legacy method."
+ *
+ * @author  unascribed
+ * @see     java.lang.Class#forName(java.lang.String)
+ * @see     java.lang.ClassLoader#findSystemClass(java.lang.String)
+ * @see     java.lang.ClassLoader#loadClass(java.lang.String, boolean)
+ * @since   JDK1.0
+ */
+public class ClassNotFoundException extends ReflectiveOperationException {
+    /**
+     * use serialVersionUID from JDK 1.1.X for interoperability
+     */
+     private static final long serialVersionUID = 9176873029745254542L;
+
+    /**
+     * This field holds the exception ex if the
+     * ClassNotFoundException(String s, Throwable ex) constructor was
+     * used to instantiate the object
+     * @serial
+     * @since 1.2
+     */
+    private Throwable ex;
+
+    /**
+     * Constructs a <code>ClassNotFoundException</code> with no detail message.
+     */
+    public ClassNotFoundException() {
+        super((Throwable)null);  // Disallow initCause
+    }
+
+    /**
+     * Constructs a <code>ClassNotFoundException</code> with the
+     * specified detail message.
+     *
+     * @param   s   the detail message.
+     */
+    public ClassNotFoundException(String s) {
+        super(s, null);  //  Disallow initCause
+    }
+
+    /**
+     * Constructs a <code>ClassNotFoundException</code> with the
+     * specified detail message and optional exception that was
+     * raised while loading the class.
+     *
+     * @param s the detail message
+     * @param ex the exception that was raised while loading the class
+     * @since 1.2
+     */
+    public ClassNotFoundException(String s, Throwable ex) {
+        super(s, null);  //  Disallow initCause
+        this.ex = ex;
+    }
+
+    /**
+     * Returns the exception that was raised if an error occurred while
+     * attempting to load the class. Otherwise, returns <tt>null</tt>.
+     *
+     * <p>This method predates the general-purpose exception chaining facility.
+     * The {@link Throwable#getCause()} method is now the preferred means of
+     * obtaining this information.
+     *
+     * @return the <code>Exception</code> that was raised while loading a class
+     * @since 1.2
+     */
+    public Throwable getException() {
+        return ex;
+    }
+
+    /**
+     * Returns the cause of this exception (the exception that was raised
+     * if an error occurred while attempting to load the class; otherwise
+     * <tt>null</tt>).
+     *
+     * @return  the cause of this exception.
+     * @since   1.4
+     */
+    public Throwable getCause() {
+        return ex;
+    }
+}