private static Set<String> ensureMutability(final Set<String> failedNodes) {
    if (failedNodes == Collections.EMPTY_SET) {
      return new HashSet<>();
    }
    return failedNodes;
  }
Does a execute Function on a server using connections from the given pool to communicate with
the server.
geode-core/src/main/java/org/apache/geode/cache/client/internal/ExecuteRegionFunctionOp.java