When the return value of a function call contains the operation status code, this value should be tested to make sure the operation completed successfully.



This rule raises an issue when the return values of the following are ignored:

* `java.io.File` operations that return a status code (except `mkdirs`)
* `Iterator.hasNext()`
* `Enumeration.hasMoreElements()`
* `Lock.tryLock()`
* non-void ``++Condition.await*++`` methods
* `CountDownLatch.await(long, TimeUnit)`
* `Semaphore.tryAcquire`
* `BlockingQueue`: `offer`, `remove`
