Consider defaulting to UTF-8 in RestClientResponseException

[ask4gilles]

Spring version: 5.2.0.RELEASE

Related to #22954 and the UTF-8 charset removal, the RestClientResponseException now defaults to ISO_8859_1 here

spring-framework/spring-web/src/main/java/org/springframework/web/client/RestClientResponseException.java

Line 105 in 3a0f309

if (this.responseCharset == null) {

instead of UTF-8 previously.

To mitigate this issue, we are now forced to create a custom ResponseErrorHandler and forcing UTF-8

[rstoyanchev]

This issue is superseded by #23764.