JMX agent get cluster name using value from another item key

[ledgewatcher]

Hi

We have nearly 50 java nodes, most are configured in clusters, comprising of 3 nodes in each cluster.
The Zabbix version is 3.0 LTS.
I have two items configured, one to discover the cluster name from key;

jmx["javanode:name=Node","ClusterNameLive"]

and another to count the number of nodes from key;

jmx["JGroups:type=protocol,cluster=javanode1,protocol= GMS","NumMembers"]

The count of nodes in the cluster works fine if the clustername is hardcoded to each node.
I would like to be able to use the value returned by the cluster name discovery item within the cluster count check, so it does not need to be hardcoded.
Using jmx["JGroups:type=protocol,cluster=getClusterName(),pr otocol=GMS","NumMembers"] goes unsupported.

Thanks in advance.