public void addFieldRankType(String field, String type) {
        verifyThat(! fieldsRankType.containsKey(field), "already has rank type for field", field);
        fieldsRankType.put(field, type);
    }
This class holds the extracted information after parsing a
rank-profile 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/ParsedRankProfile.java