public void updateType(Type type) {
        if (this.type == null) {
            this.type = type;
        } else if ((this.type == Type.BTREE) && (type == Type.HASH)) {
            this.type = Type.BTREE_AND_HASH;
        } else if ((this.type == Type.HASH) && (type == Type.BTREE)) {
            this.type = Type.BTREE_AND_HASH;
        } else {
            throw new IllegalArgumentException("Can not combine previous dictionary setting " + this.type +
                                               " with current " + type);
        }
    }
Represents settings for dictionary control

@author baldersheim
config-model/src/main/java/com/yahoo/schema/document/Dictionary.java