4.x Metrics JSON output lacks percentile and bucket entries

[tjquinno]

Environment Details

• Helidon Version: 4.x
• Helidon SE or Helidon MP
• JDK version:
• OS:
• Docker version (if applicable):

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Problem Description

The JSON output format (no longer required by MP metrics but retained as a nice feature in Helidon 4.x) omits percentile and bucket output from timers and distribution summaries (histograms).

Steps to reproduce

Declare a timer (via a @Timed annotation in MP or

Metrics.globalRegistry().getOrCreate(Timer.builder("myTimer"));

in an app.

Then retrieve the JSON metrics output using curl -H "Accept: application/json" 'http://localhost:8080/observe/metrics'. The output does not include any percentiles (which Helidon sets up by default) or buckets (which are not created unless the app code assigns them for the timer or distribution summary).