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
private static final String IMG_DEC_FIELD_ERROR = "org.eclipse.jface.fieldassist.IMG_DEC_FIELD_ERROR"; 
	private static final String IMG_DEC_FIELD_WARNING = "org.eclipse.jface.fieldassist.IMG_DEC_FIELD_WARNING"; 
	/*
	 * Declare images and decorations immediately.
	 */
	static {
		ImageRegistry imageRegistry = JFaceResources.getImageRegistry();
		
		imageRegistry.put(IMG_DEC_FIELD_CONTENT_PROPOSAL, ImageDescriptor
				.createFromFile(FieldDecorationRegistry.class,
						"images/content_proposal_cue.gif"));
		imageRegistry.put(IMG_DEC_FIELD_ERROR, ImageDescriptor.createFromFile(
				FieldDecorationRegistry.class, "images/error_cue.gif"));
		imageRegistry.put(IMG_DEC_FIELD_WARNING, ImageDescriptor
				.createFromFile(FieldDecorationRegistry.class,
						"images/warning_cue.gif"));
		imageRegistry.put(IMG_DEC_FIELD_REQUIRED, ImageDescriptor
				.createFromFile(FieldDecorationRegistry.class,
						"images/required_field_cue.gif"));		
		
		
		getDefault()
				.registerFieldDecoration(
						DEC_CONTENT_PROPOSAL,
						JFaceResources
								.getString("FieldDecorationRegistry.contentAssistMessage"), 
						IMG_DEC_FIELD_CONTENT_PROPOSAL, imageRegistry);
		getDefault().registerFieldDecoration(
				DEC_ERROR,
				JFaceResources