Memory leak in TypeGuardedDecoding in 4.x

[stswn]

TypeGuardedDecoding uses scala.reflect.api.Types.TypeApi#<:< and that causes memory leak in scala reflection Undolog as described here: scala/bug#8302

We have noticed memory leak in our application after consuming several millions of Avro messages. After analyzing heap dumps we have concluded that it is Undolog issue. We have found out that the only place that uses Undolog is in fact TypeGuardedDecoding. When we migrated derived decoder in favor of manually written one, memory issues disappeared.

I believe that in order to encounter this issue you must use either Either or shapeless coproduct in your model.