This commit updates "simple" configuration classes to use constructor
injection. Simple means that there are no optional dependencies
(@Autowired(required=false) is not used), and none of the dependencies
use generics.
Configuration classes that are not simple will be updated in a second
pass once https://jira.spring.io/browse/SPR-14015 has been fixed.
See gh-5306
Users can add @ExportMetric[Reader,Writer] to readers and writers that
they want to participate in the default exporter. There is also still an
@ActuatorMetricWriter that is used for the legacy (non-Java8) Gauge and
CounterServices.
The redis export and aggregate use case is a lot nicer with this
shared data between the two component types.
Also made MetricExportProperties itself a Trigger (so the default
delay etc. can be configured via spring.metrics.export.*).
Andy Wilkinson
Phillip Webb
Dave Syer