8252827: Caching Integer.toString just like Integer.valueOf

[Raffaello Giulietti]

Hello,

does the enhancement proposed in [1] make sense, both today and when 
wrappers will be migrated to primitive classes?
If so, it should be rather simple to add it and I could prepare a PR.
If not, the issue might perhaps be closed.


Greetings
Raffaello

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[1] https://bugs.openjdk.java.net/browse/JDK-8252827