code: public boolean markFree() {
  		if (isEmpty()) {
  			state = TaskSlotState.FREE;
  			this.jobId = null;
  			this.allocationId = null;
  
  			return true;
  		} else {
  			return false;
  		}
  	}
docs: Mark the slot as free. A slot can only be marked as free if it's empty.
  
  @return True if the new state is free; otherwise false