public synchronized void addFailedKeys(Collection<KeyCacheObject> keys,Throwable e,GridCacheContext ctx){
  if (failedKeys == null)   failedKeys=new ArrayList<>(keys.size());
  failedKeys.addAll(keys);
  if (err == null)   err=new IgniteCheckedException("Failed to update keys on primary node.");
  err.addSuppressed(e);
}

public synchronized void addFailedKeys ( Collection < KeyCacheObject > keys , Throwable e , GridCacheContext ctx ) { if ( failedKeys == null ) failedKeys = new ArrayList < > ( keys . size ( ) ) ; failedKeys . addAll ( keys ) ; if ( err == null ) err = new IgniteCheckedException ( "Failed to update keys on primary node." ) ; err . addSuppressed ( e ) ; }
adds keys to collection of failed keys .
