question: public MultiwayPoolBuilder < K , R > expireAfterWrite ( long duration , TimeUnit unit ) { checkState ( expireAfterWriteNanos == UNSET_INT , "expireAfterWrite was already set to %s ns" , expireAfterWriteNanos ) ; checkArgument ( duration >= 0 , "duration cannot be negative: %s %s" , duration , unit ) ; expireAfterWriteNanos = unit . toNanos ( duration ) ; return this ; }
target:  Specifies that each resource should be automatically removed from the pool once a fixed duration has elapsed after the resource's creation.