udunits/src/main/java/ucar/units/OffsetUnit.java
@Override
    protected Unit myDivideBy(final Unit that) throws OperationException {
        return that instanceof OffsetUnit
                ? getUnit().divideBy(((OffsetUnit) that).getUnit())
                : getUnit().divideBy(that);
    }
@Override
    protected Unit myDivideBy(final Unit that) throws OperationException {
        return that instanceof OffsetUnit
                ? getUnit().divideBy(((OffsetUnit) that).getUnit())
                : getUnit().divideBy(that);
    }
Divide this unit by another unit.

@param that
The unit to divide this unit by.
@return The quotient of this unit and <code>that</code>. The offset of
this unit will be ignored; thus, for example
"celsius.myDivideBy(day)" is equivalent to
"kelvin.myDivideBy(day)".
@throws OperationException
Can't divide these units.