IllegalArgumentException: Negated params are not supported

[ragnor]

After updating from 4.0.x to 4.1.4 I've noticed that my services cannot startup due to:

Caused by: java.lang.IllegalArgumentException: Negated params are not supported: !sync
at org.springframework.cloud.openfeign.support.SpringMvcContract.parseParams(SpringMvcContract.java:372) ~[spring-cloud-openfeign-core-4.1.4.jar:4.1.4]
at org.springframework.cloud.openfeign.support.SpringMvcContract.processAnnotationOnMethod(SpringMvcContract.java:249) ~[spring-cloud-openfeign-core-4.1.4.jar:4.1.4]
at feign.Contract$BaseContract.parseAndValidateMetadata(Contract.java:112) ~[feign-core-13.5.jar:na]
at org.springframework.cloud.openfeign.support.SpringMvcContract.parseAndValidateMetadata(SpringMvcContract.java:198) ~[spring-cloud-openfeign-core-4.1.4.jar:4.1.4]
at feign.Contract$BaseContract.parseAndValidateMetadata(Contract.java:71) ~[feign-core-13.5.jar:na]
at feign.ReflectiveFeign$ParseHandlersByName.apply(ReflectiveFeign.java:140) ~[feign-core-13.5.jar:na]
at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:59) ~[feign-core-13.5.jar:na]
at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:51) ~[feign-core-13.5.jar:na]
at feign.Feign$Builder.target(Feign.java:202) ~[feign-core-13.5.jar:na]
at org.springframework.cloud.openfeign.DefaultTargeter.target(DefaultTargeter.java:30) ~[spring-cloud-openfeign-core-4.1.4.jar:4.1.4]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:504) ~[spring-cloud-openfeign-core-4.1.4.jar:4.1.4]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:456) ~[spring-cloud-openfeign-core-4.1.4.jar:4.1.4]
at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:182) ~[spring-beans-6.1.15.jar:6.1.15]
... 29 common frames omitted

Changes were introduced by c276f1c#diff-d7125c419c7e91db20fe7e903b744c180165b6271b6d68e5b966760eb1a3c067.

Is there any way to disable this check in SpringMvcContract?
I understand that feign doesn't use negated parameters but I use shared interfaces between server and client. Negated parameters are needed on server side to avoid ambiguous mappings.

[ragnor]

I've noticed that Spring Cloud OpenFeign is already in maintenance mode and I should migrate to Spring Interface Clients.

Is there any official guide how to perform migration?

Does Spring Cloud OpenFeign support *Exchange annotations (e.g. @HttpExchange) so as a first step in migration I can change mapping descriptions in interfaces?