private boolean annotationsEquals(SpanTree tree) {
        List<Annotation> annotationCollection = new LinkedList<Annotation>(getAnnotations());
        List<Annotation> otherAnnotations = new LinkedList<Annotation>(tree.getAnnotations());

        return annotationCollection.size() == otherAnnotations.size() &&
                ImmutableMultiset.copyOf(annotationCollection).equals(ImmutableMultiset.copyOf(otherAnnotations));
    }
Returns the StringFieldValue that this SpanTree belongs to.

@return the StringFieldValue that this SpanTree belongs to, if any, otherwise null.
document/src/main/java/com/yahoo/document/annotation/SpanTree.java