@Override
    public Object get(CompoundName name, Map<String,String> context,
                                com.yahoo.processing.request.Properties substitution) {
        if ( ! properties.containsKey(name)) return super.get(name,context,substitution);
        return properties.get(name);
    }
Return true if this value should be set in this map, false if the set should be propagated instead
This default implementation always returns true.
container-search/src/main/java/com/yahoo/search/query/properties/PropertyMap.java