Bug 125420 [Commands] parameters: allow commands to specify return type
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/CommandEvent.java
/**
	 * The bit used to represent whether the command has changed its category.
	 */
	private static final int CHANGED_CATEGORY = LAST_USED_BIT << 1;
	/**
	 * The bit used to represent whether the command has changed its handler.
	 */
	private static final int CHANGED_HANDLED = LAST_USED_BIT << 2;
	/**
	 * The bit used to represent whether the command has changed its parameters.
	 */
	private static final int CHANGED_PARAMETERS = LAST_USED_BIT << 3;
	/**
	 * The command that has changed; this value is never <code>null</code>.
	 */
	private final Command command;
	/**
	 * Creates a new instance of this class.
	 * 
	 * @param command
	 *            the instance of the interface that changed.
	 * @param categoryChanged
	 *            <code>true</code>, iff the category property changed.
	 * @param definedChanged
	 *            <code>true</code>, iff the defined property changed.
	 * @param descriptionChanged
	 *            <code>true</code>, iff the description property changed.
	 * @param handledChanged