private void applyDefaultsRecursive(Cursor cursor, InnerCNode def) {
        if (def.isArray) {
            applyDefaultsToArray(cursor, def);
        } else if (def.isMap) {
            applyDefaultsToMap(cursor, def);
        } else {
            applyDefaultsToObject(cursor, def);
        }
    }
Applies default values of a given config definition to a slime payload.
TODO: Support giving correct type of default values

@author Ulf Lilleengen
config/src/main/java/com/yahoo/vespa/config/DefaultValueApplier.java