AbstractUnit.asType() will accept any si-units as valid class input

[xKrummy]

Problem:

We are using the framework within our project and do some tweaks to ensure that the dimension is always specific and correctly set (so we don't need to use wildcards in our quantites).

When we want to create a unit from a String, we use the AbstractUnit method call "asType" to ensure that the unit can be parsed into the correct dimension.
This works well for Units from thejavax.measure:unit-api(2.2) but not for the si.uom:si-quantity (2.2).

Reason:

The current implementation looks like this:

public final <T extends Quantity<T>> Unit<T> asType(Class<T> type) {
	Dimension typeDimension = UnitDimension.of(type);
	if (typeDimension != null && !typeDimension.equals(this.getDimension()))
		throw new ClassCastException("The unit: " + this + " is not compatible with quantities of type " + type);
	return (Unit<T>) this;
}

and UnitDimension.of(type) returns always null for the SI-Units

How to reproduce:

var unitAsString = "kg/h/l";
var unit = AbstractUnit.parse(unitAsString);

// The following should make sure that the given unit from string is matching the expected dimension. It will
// throw an exception if it does not match for javax units, but not for si-quantity unit.
var mass = unit.asType(Mass.class); // throws error -> correct
var dimensionless = unit.asType(Dimensionless.class); // throws error -> correct
var density = unit.asType(Density.class); // no error -> incorrect
var luminance = unit.asType(Luminance.class); // no error -> incorrect

var unitKilogramPerLiter = Units.KILOGRAM.divide(Units.HOUR.divide(Units.LITRE));

assertEquals(unitKilogramPerLiter.toString(), density.toString()); // success -> incorrect behaviour
assertEquals(unitKilogramPerLiter.toString(), luminance.toString()); // success -> incorrect behaviour

Correct behaviour (throwing errors)	Incorrect behaviour (no errors thrown)

[keilw]

I changed this to feature, because UnitDimension.of() states it returns

results from the default {@link javax.measure.spi.SystemOfUnits SystemOfUnits} or null if the specified
quantity is unknown

And in this case the types from other unit systems are just unknown. It also has a TODO for new or custom types.

Unfortunately it is not possible to go over all the registered unit systems via their service providers because AbstractUnit.asType() is called throughout the static declaration of unit constants, and trying to call the ServiceProvider there won't work, it creates some kind of "chicken and egg" problem during the initialization and causes initialization errors.