Bug 134856 [DataBinding] ValueDiff overrides Object.equals(Object) but not Object.hashCode()
The javadoc for Object.hashCode() states: "If two objects are equal according to the <tt>equals(Object)</tt> method, then calling the <code>hashCode</code> method on each of the two objects must produce the same integer result." The other IDiff implementations don't override Object.equals(Object) so I assume ValueDiff shouldn't either.
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/observable/value/ValueDiff.java
/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/
package org.eclipse.jface.databinding.observable.value;
import org.eclipse.jface.databinding.observable.Diffs;
import org.eclipse.jface.databinding.observable.IDiff;
/**
 * @since 1.0
 * 
 */
public abstract class ValueDiff implements IDiff {
	/**
	 * Creates a value diff.
	 */
	public ValueDiff() {
	}
	/**
	 * @return the old value
	 */
	public abstract Object getOldValue();