private void validateConfigDefinition(ConfigKey<?> configKey, DefContent defContent) {
        if (defContent.isEmpty()) {
            ConfigDefinitionKey configDefinitionKey = new ConfigDefinitionKey(configKey.getName(), configKey.getNamespace());
            ConfigDefinition configDefinition = configDefinitionRepo.getConfigDefinitions().get(configDefinitionKey);
            if (configDefinition == null) {
                throw new UnknownConfigDefinitionException("Unable to find config definition for '" + configKey.getNamespace() + "." + configKey.getName());
            }
        } else {
            DefParser dParser = new DefParser(configKey.getName(), new StringReader(defContent.asString()));
            dParser.getTree();
        }
    }
Resolves global config for given request.

@param request The {@link com.yahoo.vespa.config.GetConfigRequest} to find config for.
@return a {@link com.yahoo.vespa.config.protocol.ConfigResponse} containing the response for this request.
@throws java.lang.IllegalArgumentException if no such config was found.
configserver/src/main/java/com/yahoo/vespa/config/server/SuperModelController.java