@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof SpanNode2AnnotationContainer)) return false;
        SpanNode2AnnotationContainer that = (SpanNode2AnnotationContainer) o;
        if (!spanNode2Annotation.equals(that.spanNode2Annotation)) return false;
        return true;
    }
TODO: Should this be removed?

@author Einar M R Rosenvinge
document/src/main/java/com/yahoo/document/annotation/SpanNode2AnnotationContainer.java