Using newString(bytes[]) to store as cache key in hazelcast cache

I have a cache which accepts only string as keys. This cache is a part of a legacy system and I cannot modify them. To use this cache I need to convert my cache keys into string.

To make my cache keys to string am serializing it using KRYO. Converting them to bytes[] and the creating a string out of the bytes[]. Do you guys see any issues in doing this? am using the below code to convert into bytes[] Getting bytes [] uses Kryo :- final Kryo kyroInstance = serializerInstance.get(); kyroInstance.writeObject(output, target); output.getBuffer();

Reading the key as below using KRYO

final Kryo kyroInstance = serializerInstance.get();
Object obj = kyroInstance.readObject(input, type);
return obj;

I have 2 questions here 1. Is this approach looks good to you ? Do you have any other approach for my used case. 2. Am getting errors NPE sometimes while reading the keys in a distributed environment and the issue is specific to KRYO serialization.

java.lang.IndexOutOfBoundsException: Index: 34120126, Size: 0 at
java.util.ArrayList.rangeCheck(ArrayList.java:653) at
java.util.ArrayList.get(ArrayList.java:429) at
com.esotericsoftware.kryo.util.MapReferenceResolver.getReadObject(MapReferenceResolver.java:42)
    at com.esotericsoftware.kryo.Kryo.readReferenceOrNull(Kryo.java:830)
    at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:680)