AddFilterArg - not working

```js
schemaComposer.rootQuery().addFields({
entityMany: EntityTC.mongooseResolvers.findMany().addFilterArg({
name: 'test',
type: 'String',
description: 'Test',
query: (query, value, resolveParams) => {
query.name = new RegExp(value, 'i');
},
});
});
```
When I try to use this approach to adding a filter to a resolver, it doesn't throw an error. I can confirm that the filter arg is added to the resolver. But the new filter arg is not added to the schema. Is there a better way to do this?

What is the correct approach to add a filter arg to an existing resolver?

Other clues/facts:
* I'm using the most recent versions of all graphql-compose packages.
* I discovered that addFilterArg adds the field 'test' to the filter arg when I inspect it. If I subsequently take that resolver and `.clone({name: 'sample' })` the field is not in the cloned resolver. And, similarly, the field is not added to the schema.