Upgraded Q -> 2 from #19 [1685157301242]

Judge has assessed an item in Issue 19 as 2 risk. The relevant finding follows: 1. The first staker of the wxETH can get all the unlocked rewards immediately in the same block. code lines: For the first staker of the wxETH, the totalSupply of the wxETH is 0. So he can wrap the xETH to wxETH as 1:...