@Override
        public boolean isLoggable(LogRecord record) {
            if (record.getLoggerName() == null) return true;
            if (!record.getLoggerName().startsWith("org.apache.zookeeper.") &&
                    !record.getLoggerName().startsWith("org.apache.curator")) {
                return true;
            }
            fileHandler.publish(record);
            return false;
        }
Return true if loggable (ordinary log record), returns false if this filter
logs the log record itself

@param record a #{@link LogRecord}
@return true if loggable, false otherwise
vespalog/src/main/java/com/yahoo/log/LogSetup.java