udunits/src/main/java/ucar/units/LogarithmicUnit.java
@Override
    protected Unit myMultiplyBy(final Unit that) throws MultiplyException {
        if (!that.isDimensionless()) {
            throw new MultiplyException(that);
        }
        return that instanceof ScaledUnit
                ? new ScaledUnit(((ScaledUnit) that).getScale(), this)
                : this;
    }
@Override
    protected Unit myMultiplyBy(final Unit that) throws MultiplyException {
        if (!that.isDimensionless()) {
            throw new MultiplyException(that);
        }
        return that instanceof ScaledUnit
                ? new ScaledUnit(((ScaledUnit) that).getScale(), this)
                : this;
    }
Multiply this unit by another unit.

@param that
The unit to multiply this unit by. Must be dimensionless.
@return The product of this unit and <code>that</code>.
@throws MultiplyException
Can't multiply these units together.