static shallowCloneObject(original) {
    const clone = /** @type {?} */({});
    for (const k in original) {
      clone[k] = original[k];
    }
    return clone;
  }
Performs a shallow clone of the given simple object.  This does not copy
prototypes or custom properties (e.g. read-only).

@template T
@param {T} original
@return {T}