ObjectInputStream - Use new convenience method for immutable Map creation during static initialization

FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
On java.io.ObjectInputStream there are a few minor mistakes.

1) Line #536: 'Object curObj = ctx.getObj();' is set when the variable "curObj" is never used at any point of the scope

2) Line #217: '= new HashMap<>(8, 1.0F);' The initial allocation should be 9, not 8 as there are 9 entries added in the static constructor.

3) Line #42: 'import java.util.concurrent.atomic.AtomicBoolean;" AtomicBoolean is imported, but never used




REPRODUCIBILITY :
This bug can be reproduced always.