[Java][Spring] useRecords: allOf families as an interface and flat records

SE
7h ago
+1719-527

Sixth step towards #10490, allOf. With useRecords, a family one level below a parent with a discriminator becomes an interface for the parent, keeping the type-info block, and a flat record per child. A family that cannot, such as one with a redeclared property, stays classes and the reason is logged. Unlike the class, the parent can no longer be read under its own name.

@cachescrubber @welshm @MelleD @atextor @manedev79 @javisst @borsch @banlevente @Zomzog @martin-mfg @KannaKim

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Summary by cubic

Continues the useRecords work by turning allOf families into interfaces and flat records. A parent with a discriminator whose children extend it one level down becomes a sealed (with useSealed) interface that keeps the type-info annotations and declares an annotated accessor for each property; each child becomes a record that implements the parent, contains all family properties, and has a builder covering all components. Families that cannot be represented this way (a deeper hierarchy, a redeclared property, a parent with additionalProperties, a member bound from request parameters, and others) stay classes, and the log names the parent and the cause.

The parent can no longer be deserialized under its own name; only the children records are usable as JSON payloads.