void ensureMappingsExistForFieldName(String fieldName) {
        if (fieldNameMappingCache.containsKey(fieldName)) {
            return;
        }
        String dissectionName = fieldName
            .replaceAll("([A-Z])", "_$1")
            .toLowerCase(Locale.ENGLISH)
            .replaceFirst("_", "");

        fieldNameMappingCache.put(fieldName, dissectionName);
        dissectionNameMappingCache.put(dissectionName, fieldName);
    }
@param rawParameter For this dissector it is a '|' separated list of resource paths.
udfs/logparser/src/main/java/nl/basjes/parse/useragent/dissector/UserAgentDissector.java