private Stream<ConfiguredNode> availableNodesIn(Group g) {
            // We consider nodes in states (u)p, (i)nitializing, (m)aintenance as being
            // available from the perspective of taking entire groups down (even though
            // maintenance mode is a half-truth in this regard).
            return g.getNodes().stream().filter(n -> nodeIsAvailableInState(n.index(), "uim"));
        }
If the number of nodes safely set to maintenance is at least this number, the remaining
nodes in the group will be set to maintenance (storage nodes) or down (distributors).

<p>This feature is disabled if safeMaintenanceGroupThreshold is 0 (not default).</p>
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/GroupAvailabilityCalculator.java