CORS detection for reactive stack on tomcat/netty is broken [SPR-17396]

[spring-projects-issues]

Johannes Edmeier opened SPR-17396 and commented

The CorsUtils queries the presence of the Origin and Access-Control-Request-Method with a simple non null check. But when using the reactive stack the TomcatHeadersAdapter#get() and the NettyHeadersAdapter#get() returns an empty list (instead of null) when the requested header is not present.
The effect of this is, that OPTIONS requests aren't handled with the (correct) annotated handler method but are incorrectly handled as preflight requests (which they aren't)

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Affects: 5.1.1

Issue Links:

• Improve WebFlux performance for header management [SPR-17250] #21783 Improve WebFlux performance for header management

[spring-projects-issues]

Brian Clozel commented

Thanks Johannes Edmeier!