@Override
        public String toString() {
            List<String> reasons = new ArrayList<>();
            if (insufficientVcpu) reasons.add("insufficientVcpu");
            if (insufficientMemoryGb) reasons.add("insufficientMemoryGb");
            if (insufficientDiskGb) reasons.add("insufficientDiskGb");
            if (incompatibleDiskSpeed) reasons.add("incompatibleDiskSpeed");
            if (incompatibleStorageType) reasons.add("incompatibleStorageType");
            if (incompatibleArchitecture) reasons.add("incompatibleArchitecture");
            if (insufficientAvailableIPs) reasons.add("insufficientAvailableIPs");
            if (violatesParentHostPolicy) reasons.add("violatesParentHostPolicy");

            return String.format("[%s]", String.join(", ", reasons));
        }
Keeps track of the reason why a host rejected an allocation.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/CapacityChecker.java