String nameOf(Object type) {
        return toUniqueNames.computeIfAbsent(type, t -> makeUniqueName(t));
    }
Class to produce unique names for DataType instances that have
different contents even when their getName() and getId() may be
equal.

@author arnej
config-model/src/main/java/com/yahoo/vespa/configmodel/producers/DataTypeRecognizer.java