public void addAnnotation(ParsedAnnotation annotation) {
        String annName = annotation.name();
        verifyThat(! docAnnotations.containsKey(annName), "already has annotation", annName);
        docAnnotations.put(annName, annotation);
        annotation.tagOwner(this);
    }
This class holds the extracted information after parsing a
"document" block in a schema (.sd) file, using simple data
structures as far as possible.  Do not put advanced logic here!
@author arnej27959
config-model/src/main/java/com/yahoo/schema/parser/ParsedDocument.java