[phraktle]

Fixes #380.

A missing component no longer forces _recordBuild when stock would give it the local's initial value: not required, no null-handling override, and an ALWAYS_NULL deserializer (or a stock scalar, for primitives). FAIL_ON_MISSING_CREATOR_PROPERTIES still takes the stock path. Other components, such as Optional, JsonNode and @JsonSetter(nulls = ...), are unchanged.

Reproducer from #378, record with one absent String: 475 ns / 1536 B → 375 ns / 1128 B, same as all components present (379 ns / 1120 B).

BBCodecRecordAbsentTest compares with stock across component kinds and the relevant features.

[cowtowncoder]

3.3 is the right branch -- excellent.

[stevenschlansker]

Claude Opus 5.5 reviewer:

 #381: no slow path when a record component is missing (fixes #380)

 The bytecode change is fine. The bug is in how absentIsDefault() decides which missing components can use the direct path. For a non-primitive component, it only checks that getNullAccessPattern() == ALWAYS_NULL. Stock fills a missing
 component with getAbsentValue(), and that is not always null:
 - BaseScalarOptionalDeserializer, the parent of the three primitive Optional* deserializers, extends StdScalarDeserializer. It inherits ALWAYS_NULL but overrides getNullValue to return the empty Optional.
 - The probe test record Opts(String s, OptionalInt i, OptionalLong l, OptionalDouble d) read from {"s":"x"} gives this:
   - Stock: i=OptionalInt.empty, l=OptionalLong.empty, d=OptionalDouble.empty
   - #381: i=null, l=null, d=null 
 - The same happens for a generic Envelope<OptionalInt>, so the bug reaches the envelope use case behind both issues.
 - The same probe passes on #379 alone, so #381 causes it.

 Suggested fix: apply the absent shortcut only where Blackbird knows the deserializer:
 - the stock scalar kinds from STOCK_SCALAR_DESERS; 
 - CHILD codecs, whose BeanDeserializerBase reports ALWAYS_NULL and does not override the null or absent value.

 Keep Kind.STOCK on the slow path. That still covers #380's String err case.
 - Alternative: require that the deserializer overrides neither getNullValue nor getAbsentValue, checked by reflection. The allowlist above is simpler.
 - Test: add OptionalInt/OptionalLong/OptionalDouble and a converting deserializer to BBCodecRecordAbsentTest.