Interceptor that allows invocations only when cluster is formed of N nodes

Following from https://github.com/pmuir/infinispan-examples/commit/f5d090092fa7b3660025b571af29882c720bb987#L6R12

It'd be great to have an configurable StrictCluster interceptor in Infinispan which would basically make all invocations wait until the cluster of N nodes has been formed. I think it'd be a great addition and would allow clients to verify whether the cluster actually forms without the need to verify whether data replicates...etc.

In principle, the configuration would be at the CacheManager, i.e.:

<transport strictNumMembers="4"... />

However, it could also be useful to configure it at the cache level. So, could maybe want to do this: I want cache X to allow invocations the moment I have 2 nodes (in spite of the cluster being formed of 4 noes), whereas I want cache Y to allow invocations once I have 3 nodes.

Apart from an strict number of nodes, you could have a minimum number of nodes: allow invocations once I have 4 or more nodes. The strict value could still be useful to make sure intrusive machines don't get into the cluster, i.e. I expect 4 nodes in the cluster and if I have 5, something is wrong.

I think it's an interesting concept that would get rid of cluster validation code in examples and RadarGun.