code: public static <K> void removeAll(Region<K, ?> region, Set<K> keys) {
  		if (keys == null) {
  			throw new NullPointerException();
  		}
  		if (keys.isEmpty()) {
  			// Nothing to do
  			return;
  		}
  		Function function = new RemoveAllFunction();
  
  		FunctionService.registerFunction(function);
  
  		ResultCollector<?, ?> rc = FunctionService.onRegion(region)
  				.withFilter(keys).withArgs(region.getName()).execute(function);
  		
  		// Obtain result from the collector to return
  		// only after everything is done.
  		rc.getResult();
  	}
docs: Removes several entries from region in a single hop. On partitioned
  region execution is done simultaneously on all partitions.
  
  @param <K>
  key type.
  @param region
  the region to remove entries.
  @param keys
  the keys of entries to remove.