Spring-cloud-gateway: retry POST is not working

[spencergibb]

See https://github.com/spring-cloud/spring-cloud-gateway/issues/580#issuecomment-509462611 for project to reproduce.

The problem is that the routeId is null and the event is never published to cache the body.

https://github.com/spring-cloud/spring-cloud-gateway/blob/b9df1199a29d8d2b712dcd7d6f3b56580eb37b93/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/RetryGatewayFilterFactory.java#L166-L169

[spencergibb]

To work around the problem, you need to add routeId to the retry configuration. It must match the routeId.

spring:
  cloud:
    gateway:
      routes:
      - id: greeting-service
        uri: lb://greeting-service
        predicates:
        - Path=/greeting-service/**
        filters:
        - name: RewritePath
          args:
            regexp: /greeting-service/(?<path>.*)
            replacement: /$\{path}
        - name: Retry
          args:
            routeId: greeting-service
            methods: GET,POST