private ConfigInstance.Builder resolveToBuilder(ConfigKey<?> key) {
        ConfigInstance.Builder builder = createBuilder(new ConfigDefinitionKey(key));
        getConfig(builder, key.getConfigId());
        return builder;
    }
Resolves the given config key into a correctly typed ConfigBuilder
and fills in the config from this model.

@return A new config builder with config from this model filled in
config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java