NullPointerException with empty X-Forwarded-For header

[luiz290788]

spring-boot: 2.1.3
spring-boot-actuator: 2.1.3

A NullPointerException is thrown in line 49 of ServerWebExchangeTraceableRequest because request.getRemoteAddress().getAddress() is null when you make a request with an empty X-Forwarded-For header.

You can reproduce it with a request like this

GET http://localhost:8080/some-path
X-Forwarded-For: 

The path doesn't matter because the request doesn't reach the routing system.

[snicoll]

Closing in favour of PR #16046