private Object getBuilderForStruct(String name, Class<?> currentClass) {
        String structName = capitalize(name);
        String key = constructorCacheKey(structName, name, currentClass);
        Constructor<?> constructor = constructorCache.get(key);
        if (constructor == null) {
            constructor = lookupBuilderForStruct(structName, currentClass);
            if (constructor == null) return null;
            constructorCache.put(key, constructor);
        }
        try {
            return constructor.newInstance();
        } catch (Exception e) {
            throw new RuntimeException("Could not create class '" + "'" + constructor.getDeclaringClass().getName() + "'");
        }
    }
Finds a nested class with the given <code>name</code>name in <code>clazz</code>.

@param clazz a Class
@param name a name
@return class found, or null if no class is found
config/src/main/java/com/yahoo/vespa/config/ConfigPayloadApplier.java