ID to class mapping should not be hardcoded in the service

[ravwojdyla]

This should not be hardcoded here: https://github.com/spotify/zoltar/blob/master/examples/apollo-service-example/src/main/java/com/spotify/zoltar/examples/apollo/IrisPrediction.java#L64-L67

Might come for feature spec or whatever makes sense.

[regadas]

@ravwojdyla yeah I guess we can move it to the config file for now?

[brianmartin]

Here's the original reference: https://github.com/spotify/zoltar/blob/be26e5c047f617b93e03e5287b7bcd6eec6063a1/examples/apollo-service-example/src/main/java/com/spotify/zoltar/examples/apollo/IrisPrediction.java#L64-L67

That class mapping now lives here: https://github.com/spotify/zoltar/blob/25e02e9151bb57f1ed1a2a71cb779cf2318bc407/examples/apollo-service-example/src/main/java/com/spotify/zoltar/examples/apollo/IrisPredictionHandler.java#L46-L49