Fix Java Agent InternalLogger level mapping for JUL's Config level #16060
Description
Describe the bug
Description
Currently, the Java agent's InternalLogger's mapping logic promotes JUL's CONFIG level logs to INFO level, which are also emitted when Java agent is run with its default logging output configuration otel.javaagent.logging=simple.
The JUL Logging levels documentation defines CONFIG as:
- CONFIG: A message level for static configuration messages. CONFIG messages are intended to provide a variety of static configuration information, and to assist in debugging problems that may be associated with particular configurations.
This definition implies that CONFIG level may at times contain sensitive information required for debugging and the promotion of CONFIG (debugging/configuration) messages to INFO (significant/user-facing) messages can therefore leak sensitive information in logs (See existing issue reporting such a leak).
Desired Resolution
The recommended fix is to update the severity mapping in the OpenTelemetry Java Agent to prevent JUL CONFIG logs from being promoted to OpenTelemetry INFO logs.
The INFO level is supported by both - JUL and the InternalLogger, so we can update the mapping such that JUL INFO level is mapped to OpenTelemetry INFO level.
Steps to reproduce
Instrument any Java application to emit Java Util Logging (JUL) logs with CONFIG severity and with the default otel.javaagent.logging=simple.
The logs will be seen emitted as INFO level.
Expected behavior
Messages emitted with Severity less than INFO like CONFIG should only appear in logs if explicitly desired by the end-user.
Actual behavior
Messages emitted with CONFIG get promoted to INFO level by the Java agent and end up being emitted when using the Java agent's default logging configuration (otel.javaagent.logging=simple).
Javaagent or library instrumentation version
v2.24.0, v2.15.0
Environment
JDK: 17
OS: Linux
Additional context
Discussed this issue in the SIG meeting on Jan 29th, 2026.
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