This issue was noticed in JScience v4.3.1.
If the parent argument to the AlternateUnit constructor is not a standard unit,
this results in a NullPointerException. I believe this occurs because the
string expression argument to 'new UnsupportedException(...)' references 'this',
when maybe it should use 'parent'.
The relevent code snippet from AlternateUnit(String symbol, Unit<?> parent) is
throw new UnsupportedOperationException(this
+ " is not a standard unit");