public Builder setGroupedNodeFlag(final NodeFlagGroup nodeFlagGroup,
                                          final NodeFlag nodeFlag) {
            Objects.requireNonNull(nodeFlagGroup);
            Objects.requireNonNull(nodeFlag);
            if (nodeFlags == null) {
                nodeFlags = EnumSet.noneOf(NodeFlag.class);
            }
            nodeFlagGroup.addFlag(nodeFlag, nodeFlags);
            return this;
        }
Sets the presence of nodeFlag in this node's set of {@link NodeFlag}s and
removes the other members of nodeFlagGroup
stroom-core-shared/src/main/java/stroom/explorer/shared/ExplorerNode.java