validate_skeleton_top_group_hierarchy

class ValidateSkeletonTopGroupHierarchy(plugin.MayaInstancePlugin,
                                        OptionalPyblishPluginMixin):
    """Validates top group hierarchy in the SETs
    Make sure the object inside the SETs are always top
    group of the hierarchy
    """
    order = ValidateContentsOrder + 0.05
    label = "Skeleton Rig Top Group Hierarchy"
    families = ["rig.fbx"]
    optional = True

    @classmethod
    def get_attr_defs_for_instance(cls, create_context, instance):
        """Publish attribute definitions for an instance.

        Attributes available for all families in plugin's `families` attribute.

        Args:
            create_context (CreateContext): Create context.
            instance (CreatedInstance): Instance for which attributes are
                collected.

        Returns:
            list[AbstractAttrDef]: Attribute definitions for plugin.

        """
        if instance.product_base_type != "rig":
            return []

        return cls.get_attribute_defs()

    def process(self, instance):
        if not self.is_active(instance.data):
            return

        skeleton_mesh_nodes = instance.data("skeleton_mesh", [])
        if not skeleton_mesh_nodes:
            return

        invalid = get_non_root_nodes(skeleton_mesh_nodes)
        if invalid:
            raise PublishValidationError(
                "The skeletonMesh_SET includes the object which "
                "is not at the top hierarchy: {}".format(invalid))