Reproduce RUMS-3855: invalid W3C traceparent parentId decimal encoding

[mariusc83]

Reproduction for RUMS-3855

Jira: RUMS-3855

Issue Summary

TracingInterceptor generates invalid W3C traceparent headers when a span is not sampled: it converts spanId via Long.toString() (decimal) instead of hex encoding, producing a parentId field that may exceed 16 characters. This causes "Invalid traceparent version" errors on the backend.

Reproduction Tests

Failing tests demonstrating the bug in TracingInterceptor.

What the Tests Prove

The parentId field in the generated traceparent header contains decimal digits and is not properly bounded to 16 hex characters, violating the W3C Trace Context specification.

Root Cause Analysis

TracingInterceptor.handleW3CNotSampledHeaders() calls span.context().toSpanId() which returns a decimal representation of the Long spanId (up to 20 chars) instead of the required 16-char hex string.

Call Chain

TracingInterceptor.interceptAndTrace()
→ TracingInterceptor.updateRequest() [isSampled=false branch]
→ TracingInterceptor.setSampledOutHeaders()
→ TracingInterceptor.handleW3CNotSampledHeaders(span, requestBuilder)
→ span.context().toSpanId() [returns DECIMAL, not hex]
→ W3C_TRACEPARENT_DROP_SAMPLING_DECISION.format(traceId, spanId.padStart(16, '0'))
→ addHeader('traceparent', '00-{32hex}-{decimalSpanId}-00') [>55 chars when spanId >16 decimal digits]
→ Backend: ValueError: Invalid traceparent version

Failure Output

Test 1: traceparent must be exactly 55 chars per W3C spec — actual header '00-{32hex}-9223372036854775807-00' is 58 chars (expected 55).
Test 2: traceparent must match W3C pattern '00-[0-9a-f]{32}-[0-9a-f]{16}-0[01]' — parentId '9223372036854775807' is 19 decimal digits, not 16 hex chars.

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