Members of the distributed system can fill one or more user defined roles.
A role is metadata that describes how the member relates to other members
or what purpose it fills.
Roles are specified when
connecting to the DistributedSystem.
Returns true if this role is currently present in distributed system.
If true, then at least one member in the system is configured with this
role, regardless of whether or not that member has a cache.
true if this role is currently present in distributed system
Returns the count of members currently filling this role. These members
may or may not have a cache.
number of members in system currently filling this role