docs: @Nonnull
  	public final TypeSerializer<T> previousSchemaSerializer() {
  		if (cachedRestoredSerializer != null) {
  			return cachedRestoredSerializer;
  		}
  
  		if (previousSerializerSnapshot == null) {
  			throw new UnsupportedOperationException(
  				"This provider does not contain the state's previous serializer's snapshot. Cannot provider a serializer for previous schema.");
  		}
  
  		this.cachedRestoredSerializer = previousSerializerSnapshot.restoreSerializer();
  		return cachedRestoredSerializer;
  	}