Closes the keyed object pool. Once the pool is closed,
{@link #borrowObject(Object)} will fail with IllegalStateException, but
{@link #returnObject(Object, Object)} and
{@link #invalidateObject(Object, Object)} will continue to work, with
returned objects destroyed on return.
<p>
Destroys idle instances in the pool by invoking {@link #clear()}.
Closes the keyed object pool. Once the pool is closed, {@link #borrowObject(Object)} will fail with IllegalStateException, but {@link #returnObject(Object, Object)} and {@link #invalidateObject(Object, Object)} will continue to work, with returned objects destroyed on return. <p> Destroys idle instances in the pool by invoking {@link #clear()}.