public B addOptionalResources(String resourceString) {
            failIfAlreadyBuilt();
            optionalResources.add(resourceString);
            return (B)this;
        }
Add a set of additional rules. Useful in handling specific cases.
The startup will continue even if these do not exist.
@param resourceString The resource list that should to be added.
@return the current Builder instance.
analyzer/src/main/java/nl/basjes/parse/useragent/AbstractUserAgentAnalyzerDirect.java