private Pair<String, ClassLoader> getClassLoaderForProducer(ConfigDefinitionKey key, String shortClassName) {
        // TODO: Stop supporting fullClassNameWithComYahoo below, should not be used
        String fullClassNameWithComYahoo = "com.yahoo." + key.getNamespace() + "." + shortClassName;
        String fullClassNameWithoutPrefix = key.getNamespace() + "." + shortClassName;
        String producerSuffix = "$Producer";

        ClassLoader loader = getConfigClassLoader(fullClassNameWithoutPrefix + producerSuffix);
        if (loader != null) return new Pair<>(fullClassNameWithoutPrefix, loader);

        return new Pair<>(fullClassNameWithComYahoo,
                          getConfigClassLoader(fullClassNameWithComYahoo + producerSuffix));
    }
Takes a candidate class name and tries to find a config producer for that class in the model. First, an
attempt is made with the given full class name, and if unsuccessful, then with 'com.yahoo.' prefixed to it.
Returns the full class name and the class loader that a producer was found for. If no producer was found,
returns the full class name with prefix, and null for the class loader.
config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java