Currently, prefix is spring.cloud.gateway and this is ambiguous now that server-webmvc exists.
spring.cloud.gateway.server.webflux is the new prefix
Fixes gh-3363
Previously only a warning was printed in the logs, but sometime ago, ServerCodecConfigurer was added as a bean dependency which caused apps with mvc on the classpath to fail with an error that was difficult to diagnose. The warning was changed to a failure analyzer.
Fixes gh-2176