How to use fragmentReplacements?

[electrovir]

(related to #103 (comment))

I've got some really old code that is doing this:

import {applyMiddleware} from 'graphql-middleware';
import {ReplaceFieldWithFragment, makeExecutableSchema, wrapSchema} from 'graphql-tools';

function finalizeSchema(originalSchema, permissions) {
  const {schema, fragmentReplacements} = applyMiddleware(
      originalSchema,
      permissions,
  );
  
  const transforms = [
      new ReplaceFieldWithFragment(schema, fragmentReplacements),
  ];
  const finalSchema = wrapSchema(schema, transforms);
  
  return finalSchema;
}

However, ReplaceFieldWithFragment no longer exists in any of the new @graphql-tools/* packages and I have yet to find a replacement. How am I supposed to use fragmentReplacements now?