Support of Optional for data binding [SPR-13933]

[spring-projects-issues]

Stéphane Nicoll opened SPR-13933 and commented

See spring-projects/spring-boot#5110

---

Issue Links:

• Support for injecting optional properties into a Optional<String> field [SPR-13150] #17741 Support for injecting optional properties into a Optional field

Referenced from: commits 700ab2f

[spring-projects-issues]

Juergen Hoeller commented

For the purposes of that Boot ticket, our arrangement actually works as designed: As long as a ConversionService is associated with the binder, we do wrap a given value as an Optional: either for an actual value, or as Optional.empty for a given null value.

Note that the binder does not actually set anything for unspecified properties. It strictly reacts to specified property values only. So if Optional.empty is desired for non-specified properties, the caller would have to manually add a null value for each affected property.

All in all, I would simply initialize those fields with Optional.empty(), not least of it all for the invariants of that class itself.

Juergen