Currently, class
org.netbeans.modules.editor.NbEditorUtilities
contains method

public static DataObject getDataObject(Document
doc) {...}

Since DataObject will be deprecated, it would be
useful to provide an additional method which
returns a fileobject. That way, modules which use
this utility class (e.g. JSP coloring module) do
not need to depend on the DataObjects API.

This is also related to issue 34541 (editor
support without DataObjects): this editor will not
put the DataObject as the property to the
document; instead, it will probably put a
FileObject there. So I suggest the new method is
as follows:

/** Get the fileobject from the document's   
 *  StreamDescriptionProperty property. 
 */
public static FileObject getFileObject(Document doc) {
    Object sdp = doc.getProperty(
                 Document.StreamDescriptionProperty);
    if (sdp instanceof FileObject) {
        return (FileObject)sdp;
    }
    if (sdp instanceof DataObject) {
        return ((DataObject)sdp).getPrimaryFile();
    }
    return null;
}

Also related to issue 34814 - project should be
available in the document.