feat(spring): enable `openApiNullable` with `useJackson3` #769

Job	Run time
Build JAX-RS (samples/server/petstore/jaxrs/jersey2)	46s
Build JAX-RS (samples/server/petstore/jaxrs/jersey2-useTags)	45s
Build JAX-RS (samples/server/petstore/jaxrs-spec-interface)	33s
Build JAX-RS (samples/server/petstore/jaxrs-resteasy/eap-java8)	1m 1s
Build JAX-RS (samples/server/petstore/jaxrs-spec)	50s
Build JAX-RS (samples/server/petstore/jaxrs-spec-withxml)	49s
Build JAX-RS (samples/server/petstore/jaxrs-jersey)	55s
Build JAX-RS (samples/server/petstore/jaxrs-resteasy/eap-joda)	1m 3s
Build JAX-RS (samples/server/petstore/jaxrs-cxf)	58s
Build JAX-RS (samples/server/petstore/jaxrs-resteasy/joda)	52s
Build JAX-RS (samples/server/petstore/jaxrs-cxf-non-spring-app)	54s
Build JAX-RS (samples/server/petstore/jaxrs-spec-swagger-v3-annotations)	54s
Build JAX-RS (samples/server/petstore/jaxrs-spec-swagger-annotations)	46s
Build JAX-RS (samples/server/petstore/jaxrs-resteasy/default)	52s
Build JAX-RS (samples/server/petstore/jaxrs-spec-microprofile-openapi-annotations)	53s
Build JAX-RS (samples/server/petstore/jaxrs-cxf-cdi)	1m 12s
Build JAX-RS (samples/server/petstore/jaxrs-datelib-j8)	49s
Build JAX-RS (samples/server/petstore/jaxrs-resteasy/eap)	53s
Build JAX-RS (samples/server/petstore/jaxrs-cxf-annotated-base-path)	57s
Build JAX-RS (samples/server/petstore/jaxrs-spec-swagger-v3-annotations-jakarta)	52s
Build JAX-RS (samples/server/petstore/jaxrs-spec-interface-response)	36s
	18m 10s

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