Bug 140160 [Field Assist] - JAVADOC ONLY- FieldDecorationRegistry API should specify that null dec description is allowed
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/FieldDecorationRegistry.java
/**
	 * Get the default FieldDecorationRegistry.
	 * 
	 * @return the singleton FieldDecorationRegistry that is used to manage
	 *         shared field decorations.
	 */
	public static FieldDecorationRegistry getDefault() {
		if (defaultInstance == null) {
			defaultInstance = new FieldDecorationRegistry();
		}
		return defaultInstance;
	}
	/**
	 * Set the default FieldDecorationRegistry.
	 * 
	 * @param defaultRegistry
	 *            the singleton FieldDecorationRegistry that is used to manage
	 *            shared field decorations.
	 */
	public static void setDefault(FieldDecorationRegistry defaultRegistry) {
		defaultInstance = defaultRegistry;
	}
	/**
	 * Construct a FieldDecorationRegistry.
	 */
	public FieldDecorationRegistry() {
		maxDecorationWidth = 0;
		maxDecorationHeight = 0;
	}
	/**