public static NodesSpecification requiredFromSharedParents(int count, NodeResources resources,
                                                               ModelElement element, ConfigModelContext context) {
        List<NodesSpecification> allContent = findParentByTag("services", element.getXml()).map(services -> XML.getChildren(services, "content"))
                                                                                           .orElse(List.of())
                                                                                           .stream()
                                                                                           .map(content -> new ModelElement(content).child("nodes"))
                                                                                           .filter(nodes -> nodes != null && nodes.stringAttribute("count") != null)
                                                                                           .map(nodes -> from(nodes, context))
                                                                                           .toList();
        return new NodesSpecification(new ClusterResources(count, 1, resources),
                                      new ClusterResources(count, 1, resources),
                                      IntRange.empty(),
                                      true,
                                      context.getDeployState().getWantedNodeVespaVersion(),
                                      allContent.stream().anyMatch(content -> content.required),
                                      ! context.getDeployState().getProperties().isBootstrap(),
                                      false,
                                      context.getDeployState().getWantedDockerImageRepo(),
                                      Optional.empty(),
                                      context.getDeployState().getProperties().cloudAccount(),
                                      false);
    }
Returns a requirement for {@code count} shared nodes with {@code required} taken as
the OR over all content clusters, and with the given resources.
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/NodesSpecification.java