MappedBatchLoaders in 6.x? (replacing DataLoaderFactory.newMappedDataLoader from 5.x)

[samuelAndalon]

Discussed in #1454

^{Originally posted by terminalnode June 8, 2022}
In our SpringBoot application running 5.x of graphql-kotlin-spring-server (and related libraries) we make heavy use of mapped data loaders using this pattern:

class MyDataLoader() : KotlinDataLoader<K, V> {
  override val dataLoaderName = "MyDataLoader"
  override fun getDataLoader() : DataLoader<K, V> =
    DataLoaderFactory.newMappedDataLoader(/* ... */)
}

In 6.x getDataLoader has been replaced with getBatchLoader which is supposed to return a BatchLoader<K, V>. There is MappedBatchLoader<K, V>, but that's not a BatchLoader.

How would I register mapped batch loaders in 6.x?