While working on SPR-12532, an extra IdentityWrapper was added to work
around a backward compatible issue between commons pool 1.x and 2.x. This
issue (POOL-283) has actually been fixed in 2.4 and their IdentityWrapper
is using object equality so our wrapper is in the way.

Looking retrospectively, the code looks all fine without the workaround
and commons pool 2.4 or later so it has been removed.