Spec says the value must be true or false...

11.6.1.2 Long-running Work instance Hint

The resource adapter may use the String javax.resource.LongRunning, defined as a constant in HintsContext.LONGRUNNING_HINT, as the hintName to indicate that a Work instance might run for a long period of time (typically lasting throughout the lifecycle of the resource adapter instance) compared to regular tasks that have a shorter execution lifecycle. The value of the hint must be a valid boolean value (true or false).

However the code simply checks for existence...

67                  HintsContext hc = (HintsContext) wc;
68                  if (hc.getHints().containsKey(HintsContext.LONGRUNNING_HINT))
69                  

{ 70                     isLongRunning = true; 71                     found = true; 72                  }

Hence if 'false' is provided, the wrong outcome will result.