Apache Flink

I'm getting the following exception when I attempt to run my stateful flink app with more than 1 task manager, and I'm not sure why.

```Caused by: java.lang.IllegalArgumentException: Key group 75 is not in KeyGroupRange{startKeyGroup=0, endKeyGroup=63}. Unless you're directly using low level state access APIs, this is most likely caused by non-deterministic shuffle key (hashCode and equals implementation).```
The only `KeySelector` I'm using is returning the following, which is definitely deterministic. The `AggregationType` is a valueless `enum`

```data class MetricKey(
    val name: String,
    val aggregationType: AggregationType,
    val timestamp: Long,
)```
The event stream is being fed into my `KeyedProcessFunction`
```class AggregationProcessor : KeyedProcessFunction&lt;MetricKey, Metric, AggregationResult&gt;()```
This class does hold several `AggregatingStateDescriptors` which relies on the key so that aggregations are performed with the data grouped by the key.

Any idea what to look for?

To close the loop, it was the `AggregationType` `Enum`causing weird behavior when serializing / hashcodes. I instead just stored the ordinal and now its fine