Add "AtomicLong.class" (And other Atomic* types) to the list of primitive Attribute Types at isPrimitiveAttributeType(Class<?> clazz)
/zabbix_java/src/com/zabbix/gateway/JMXItemChecker.java line 248
AtomicLong is useful for making sure your stats are consistent over many JAVA threads. As such, they are often used as JMX attributes, and act just like "Long"s as far as Zabbix is concerned.
This is a trivial fix.