NamedBuilder createBuilder(NamedBuilder parentBuilder, String name) {
        Object builder = parentBuilder.builder();
        Object newBuilder = getBuilderForStruct(name, builder.getClass().getDeclaringClass());
        if (newBuilder == null) return null;
        return new NamedBuilder((ConfigBuilder) newBuilder, name);
    }
A utility class that can be used to apply a payload to a config builder.

TODO: This can be refactored a lot, since many of the reflection methods are duplicated

@author Ulf Lilleengen
@author hmusum
@author Tony Vaagenes
config/src/main/java/com/yahoo/vespa/config/ConfigPayloadApplier.java