private static void readDevZoneEndpoint(Element endpointElement, Map<ClusterSpec.Id, ZoneEndpoint> endpoints) {
        String endpointType = getZoneEndpointType(endpointElement, Level.instance)
                .orElseThrow(() -> new IllegalArgumentException("Illegal endpoint type for <dev>: only 'zone' and 'private' endpoints are allowed"));

        if ( ! XML.getChildren(endpointElement, regionTag).isEmpty())
            throw new IllegalArgumentException("Illegal 'region' children of <endpoint> in <dev>");

        String containerId = requireStringAttribute("container-id", endpointElement);
        boolean enabled = readEnabled(endpointElement, Optional.of(endpointType), "Dev endpoint");
        List<AllowedUrn> allowedUrns = readAllowedUrns(endpointElement, Optional.of(endpointType), containerId, "Dev endpoint");

        ZoneEndpoint endpoint = switch (endpointType) {
            case "zone" -> new ZoneEndpoint(enabled, false, List.of());
            case "private" -> new ZoneEndpoint(true, true, allowedUrns); // Doesn't turn off public visibility.
            default -> throw new IllegalArgumentException("Unsupported zone endpoint type '" + endpointType + "'");
        };
        endpoints.merge(ClusterSpec.Id.from(containerId), endpoint, (o, n) -> {
            if (o.isPrivateEndpoint() == n.isPrivateEndpoint())
                throw new IllegalArgumentException("Multiple '" + (o.isPrivateEndpoint() ? "private" : "zone") +
                                                   "' type endpoints declared for container-id '" + containerId + "' in <dev>");

            return new ZoneEndpoint(o.isPublicEndpoint() && n.isPublicEndpoint(),   // Private one doesn't affect this.
                                    o.isPrivateEndpoint() || n.isPrivateEndpoint(), // One has to be private, since we merge.
                                    new ArrayList<>() {{ addAll(o.allowedUrns()); addAll(n.allowedUrns()); }});
        });
    }
Returns true if the given value is "true", or if it is missing
config-model-api/src/main/java/com/yahoo/config/application/api/xml/DeploymentSpecXmlReader.java