OTLP metric exporter accepts aggregation temporality function

[jack-berg]

I've been uncomfortable with the fact that setPreferredTemporality(AggregationTemporality) only allows two options (DELTA and CUMULATIVE) when others are possible. What would we do if OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE were to add a third option? Also, that selecting DELTA specifies a preference for delta that applies in most but not all cases.

This adjusts OtlpHttpMetricExporter and OtlpGrpcMetricExporter to accept a Function<InstrumentType, AggregationTemporality> instead of AggregationTemporality.

This offers more flexibility and would be needed in the future when we want to support alternative aggregation temporality configs besides the "cumulative" and "delta preferred". To assist with setting Function<InstrumentType, AggregationTemporality>, I've added two helper functions to MetricExporter which represent common aggregation temporality configurations.

[codecov]

Codecov Report

Merging #4340 (698c37c) into main (d3a8b32) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main    #4340      +/-   ##
============================================
+ Coverage     89.88%   89.91%   +0.02%     
- Complexity     4866     4867       +1     
============================================
  Files           568      568              
  Lines         15093    15092       -1     
  Branches       1441     1440       -1     
============================================
+ Hits          13567    13570       +3     
+ Misses         1056     1054       -2     
+ Partials        470      468       -2     

Impacted Files	Coverage Δ
...lemetry/exporter/internal/ExporterBuilderUtil.java	100.00% <ø> (ø)
...lp/http/metrics/OtlpHttpMetricExporterBuilder.java	100.00% <100.00%> (+6.25%)	⬆️
...er/otlp/metrics/OtlpGrpcMetricExporterBuilder.java	94.28% <100.00%> (+4.81%)	⬆️
...sdk/autoconfigure/MetricExporterConfiguration.java	85.93% <100.00%> (+0.45%)	⬆️
...pentelemetry/sdk/autoconfigure/OtlpConfigUtil.java	90.26% <100.00%> (+0.26%)	⬆️
...entelemetry/sdk/metrics/export/MetricExporter.java	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d3a8b32...698c37c. Read the comment docs.