Bug 17256 Exception due to bug 17208
bundles/org.eclipse.core.databinding/src/org/eclipse/core/databinding/validation/ReadOnlyValidator.java
private static ReadOnlyValidator singleton = null;
	/**
	 * Returns the ReadOnlyValidator
	 * 
	 * @return the ReadOnlyValidator
	 */
	public static ReadOnlyValidator getDefault() {
		if (singleton == null) {
			singleton = new ReadOnlyValidator();
		}
		return singleton;
	}
	public IStatus validate(Object value) {
		
		return ValidationStatus.error(BindingMessages
				.getString("Validate_NoChangeAllowedHelp")); 
	}
}