wip:milestone 0 fixes

control-plane-ui/node_modules/@mui/x-data-grid/models/gridColumnGrouping.js

@@ -0,0 +1,11 @@
+export function isLeaf(node) {
+  return node.field !== undefined;
+}
+
+/**
+ * A function used to process headerClassName params.
+ */
+
+/**
+ * The union type representing the [[GridColDef]] column header class type.
+ */