public void addAnnotation(ParsedAnnotation annotation) {
        String annName = annotation.name();
        verifyThat(! extraAnnotations.containsKey(annName), "already has annotation", annName);
        extraAnnotations.put(annName, annotation);
    }
This class holds the extracted information after parsing
one schema (.sd) file, using simple data structures
as far as possible.

Do not put complicated logic here!

@author arnej27959
config-model/src/main/java/com/yahoo/schema/parser/ParsedSchema.java