public void addIndex(ParsedIndex index) {
        String idxName = index.name();
        verifyThat(! extraIndexes.containsKey(idxName), "already has index", idxName);
        extraIndexes.put(idxName, index);
    }
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