feat(spring): enable `openApiNullable` with `useJackson3` #1155

Job	Run time
Build with JDK17 (samples/openapi3/server/petstore/springboot-3)	52s
Build with JDK17 (samples/client/petstore/java-helidon-client/v3/se)	55s
Build with JDK17 (samples/client/petstore/spring-http-interface)	46s
Build with JDK17 (samples/client/petstore/java-helidon-client/v3/mp/)	57s
Build with JDK17 (samples/client/petstore/spring-http-interface-useHttpServiceProxyFactoryInterfa...	48s
Build with JDK17 (samples/openapi3/client/petstore/spring-cloud-3)	52s
Build with JDK17 (samples/openapi3/server/petstore/springboot-3-include-http-request-context)	1m 4s
Build with JDK17 (samples/server/petstore/java-helidon-server/v3/se)	51s
Build with JDK17 (samples/server/petstore/java-helidon-server/v3/mp/)	54s
Build with JDK17 (samples/client/petstore/java/microprofile-rest-client-outer-enum)	40s
Build with JDK17 (samples/client/petstore/spring-http-interface-noResponseEntity)	49s
Build with JDK17 (samples/client/petstore/spring-http-interface-reactive-noResponseEntity)	44s
Build with JDK17 (samples/client/petstore/java/webclient-jakarta)	51s
Build with JDK17 (samples/server/petstore/springboot-x-implements-skip)	51s
Build with JDK17 (samples/client/petstore/spring-http-interface-reactive)	48s
Build with JDK17 (samples/server/petstore/java-camel/)	1m 3s
	13m 45s

Provide feedback