IEnergySink implementation mistake?

    @Override
    public int injectEnergy(Direction directionFrom, int amount) {
        if (!directionFrom.equals(Direction.YP)) {
            if (Energy >= 10000) {
                this.Energy = 10000;
                return amount;
            } else {
                int left = amount - 4;
                Energy += (amount > 4) ? 4 : amount;
                if (Energy > 10000) {
                    left += Energy - 10000;
                    Energy = 10000;
                }
                return left;
            }
        }
        return amount;
    }

    @Override
    public int getMaxSafeInput() {
        return Integer.MAX_VALUE;
    }

    @Override
    public boolean acceptsEnergyFrom(TileEntity emitter, Direction direction) {
        if (this.Energy >= 10000) {
            this.Energy = 10000;
            return false;
        }
        if (direction.equals(Direction.YN)) {
            return true;
        }
        return false;
    }

    @Override
    public boolean isAddedToEnergyNet() {
        return inEnergyNet;
    }
    @Override
    public int demandsEnergy() {
        return (Energy < 10000) ? 4 : 0;
    }