Azure Functions Java: Duplicate log entries in Portal Log Stream since agent 3.7.0

检查 PR #3962 中 agent 3.7.0 的依赖项变更，并比较 OpenTelemetry Instrumentation 2.9.0 与 2.10.0，重点关注 JUL 处理和 Portal Log Stream 路径。使用 APPLICATIONINSIGHTS_ENABLE_AGENT=true 和 context.getLogger().info() 进行复现，然后将行为与 agent 3.6.2 进行比较。完成标准是：日志在 App Insights traces 中只出现一次，且 Portal Log Stream 中没有 [undefined] 重复项。

Description

When APPLICATIONINSIGHTS_ENABLE_AGENT=true (the default), calls to context.getLogger().info() produce duplicate entries in the Azure Portal Log Stream:

• [Information] from the host RPC log pipeline
• [undefined] from the AI agent's JUL auto-instrumentation

The duplication only appears in the Portal Log Stream. In the App Insights traces table, the user log message appears once (from the agent only). The entries stored in App Insights are identical in structure between the working and broken agent versions.

Regression

Introduced in agent 3.7.0, which upgraded OpenTelemetry Java Instrumentation from 2.9.0 to 2.10.0 (PR #3962). No AI agent code changes were made between 3.6.2 and 3.7.0 regarding JUL handling. The behavioral change comes from the upstream OTel dependency bump.

With 3.6.2, the agent captures JUL logs and sends them to App Insights without producing a duplicate in the log stream. Starting with 3.7.0, the same capture also produces an [undefined] entry in the log stream.

Affects all Java versions (8, 11, 17, 21, 25) on Linux Dedicated.

Workarounds

No workaround fully restores the 3.6.2 behavior (user logs in AI traces without log stream duplication).

Expected behavior

The agent should capture JUL logs for App Insights without producing a duplicate [undefined] entry in the log stream, as it did in 3.6.2.