ASSERT.that(keySet).hasContentsAnyOrder(4, 6, 8, 0, 1, 2, 5, 7, 9);
// 4 expires
ticker.advance(1, MILLISECONDS);
ASSERT.that(keySet).hasContentsAnyOrder(6, 8, 0, 1, 2, 5, 7, 9);
ticker.advance(1, MILLISECONDS);
ASSERT.that(keySet).hasContentsAnyOrder(6, 8, 0, 1, 2, 5, 7, 9);
// 6 expires
ticker.advance(1, MILLISECONDS);
ASSERT.that(keySet).hasContentsAnyOrder(8, 0, 1, 2, 5, 7, 9);