Error-prone: Check for redundant Collection.contains calls.

[NightlyNexus]

Could Error prone check for a Collection.contains call followed by an immediate Collection.remove call?

I see a fair amount of

if (myList.contains(value)) {
  myList.remove(value);
  // Do something.
}

which could be

if (myList.remove(value)) {
  // Do something.
}

[JakeWharton]

Or add (on Set)! Or put (on Map)!

[lowasser]

This is internally covered in the tools alluded to in #649 which we are working on getting open sourced.