In my mind, a utility class is not a StringUtils-style class. It’s a class that is design to be instantiated and performs some utility task. Those utility classes typically live in ‘util’ (or ‘utils’) packages.

StringUtils is a collection of utility methods (i.e., a function library), which is a very different construct. It’s class-nature is predicated by the everything-is-an-class nature of Java and other similar languages.