public Annotations get(AnnotationClass annotationClass) {
        return rootSpan.getAnnotation(annotationClass);
    }
Returns the annotation marked with the annotationClass.

This is different from annotate(annotationClass) because a new annotation
will not be created if it does not exist.

@param annotationClass class of the annotation
@return an annotation with the given class, null if it does not exists
container-search/src/main/java/com/yahoo/text/interpretation/Interpretation.java