springboot ConnectionPool metrics are not exposed with r2dbc:pool: based URLs

See https://github.com/spring-projects-experimental/spring-boot-r2dbc/issues/80 for a description of the problem.

It looks like that when a ConnectionFactory is exposed as a @Bean (while being a ConnectionPool effectively, @ConditionalOnBean(ConnectionPool.class) does not match. I don't know if that's to be expected but that vaguely rings a bell.

We could relax the condition and then only handles ConnectionPool in the current registration code.

Comment From: snicoll

I have a "fix" for this problem but it feels a little odd that we have to do that, see https://github.com/snicoll/spring-boot/commit/3c88e65b325d00ad44cc90edda87c8894c95803d