[PATCH] 7164256 : EnumMap.clone doesn't clear the entrySet field, keeping a reference to the original Map

[Diego Belfer]

Hello,

I have reported a bug in the implementation of the clone method of the
EnumMap class.
The instance field entrySet is not being cleared, so the entrySet field of
the new instance references to the original EnumMap.

I am providing a simple patch for review. It adds one line to the clone
method that sets the entrySet field to null.

This is my first contribution to the OpenJDK, so let me know if I am
missing some step of the process.

Thanks,
Diego Belfer
[muralx]