Are there any open source libraries for representing cooking units such as Teaspoon and tablespoon in Java?
I have only found JSR-275 (https://jcp.org/en/jsr/detail?id=275) which is great but doesn't know about cooking units.
This might be of some use: JUnitConv. It's a Java applet for converting units (including cooking units), but it's GPL-licensed so you could download the source and adapt the relevant parts for your own use.
On the other hand, it looks like it shouldn't be hard to create a CookingUnits class compliant with JSR 275. (That's what I'd do)