Update data properties to make it clear which stores do and do not require Spring Data

[mbhave]

Redis properties are under spring.redis currently. This seems to be inconsistent with other stores that have properties under spring.data (eg, couchbase, cassandra, neo4j).

[philwebb]

For java packages we have a split for some technologies. For example, the org.springframework.boot.autoconfigure.mongo package contains no Spring Data bits those are only in org.springframework.boot.autoconfigure.data.mongo.

[snicoll]

Redis is a different beast in the sense that even the low-level connection stuff relies on Spring Data. In that sense the package is ok (since there is a dependency on Spring Data.

There is no reason however to bring the data part in the namespace since those keys aren't related to the Spring Data part.

I am not saying the situation is perfectly fine (I am sure we can find inconsistencies easily) but this one looks ok to me.

[philwebb]

There's a lot of inconsistency with all our data properties. We should expand the scope of this to look at them all.

[snicoll]

Note that the package structure also affects the actuator. We don't have any data package at all there and a number of support classes are effectively Spring Data specific. The current health indicator for Cassandra is a good example.