Immutable, primitive, numeric values cause a cast error when generating the key

[realityforge]

Adding code like:

  @Input( immutable = true )
  abstract int eventId();

Will produce code like:

  (int) inputs.get( React4j_EventCoordination.Inputs.eventId )

when generating key part for input which generates an error as the javascript number type (which is what is stored in the inputs map) is mapped to a java double/Double. Perhaps a way to fix this is to translate this to something like

  (int) (double) inputs.get( React4j_EventCoordination.Inputs.eventId )

however further testing is required