Spring provides two options to mark a REST parameter as optional:
- Use
required = false in the @PathVariable or @RequestParam annotation of the respective method parameter
or
- Use type
java.util.Optional<T> for the method parameter
When using 1., the absence of the parameter, when the REST function is called, is encoded by null, which can only be used for object
types. If required = false is used for a parameter with a primitive and the REST function is called without the parameter, a runtime
exception occurs because the Spring data mapper cannot map the null value to the parameter.
