Bug 125420 [Commands] parameters: allow commands to specify return type
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
&& ((DEBUG_HANDLERS_COMMAND_ID == null) || (DEBUG_HANDLERS_COMMAND_ID
						.equals(id)))) {
			final StringBuffer buffer = new StringBuffer("Command('"); 
			buffer.append(id);
			buffer.append("') has changed to "); 
			if (handler == null) {
				buffer.append("no handler"); 
			} else {
				buffer.append('\'');
				buffer.append(handler);
				buffer.append("' as its handler"); 
			}
			Tracing.printTrace("HANDLERS", buffer.toString()); 
		}
		
		fireCommandChanged(new CommandEvent(this, false, false, false, true,
				false, false));
		return true;
	}
	/**
	 * The string representation of this command -- for debugging purposes only.
	 * This string should not be shown to an end user.
	 * 
	 * @return The string representation; never <code>null</code>.
	 */
	public final String toString() {
		if (string == null) {
			final StringBuffer stringBuffer = new StringBuffer();
			stringBuffer.append("Command("); 
			stringBuffer.append(id);