This bug is only really a problem in that it can confuse people. Nodes in a Confluence cluster are successfully bound together by using a common multicast address and a blank cluster name specified in the coherence configuration.

Confluence is specifying a "cluster-name" element within the "cluster-config" element passed to Coherence. The "cluster-name" element should be within the "member-identity" element within the "cluster-config". See also http://wiki.tangosol.com/display/COH32UG/member-identity

(The warning is displayed in the logs.)