code: public Annotation previous(AnnotationType type) {
        return document() == null ? Fragments.detachedEmptyAnnotation() : document().getAnnotationSet().previous(this,
                                                                                                                 type);
     }
docs: Gets the annotation of a given type that is previous in order (of span) to this one
  
  @param type the type of annotation wanted
  @return the previous annotation of the given type or null