`SdkLogRecordBuilder` does not properly set default timestamp

[Quaffel]

Describe the bug
The javadoc for LogRecordBuilder#setTimestap states that if the timestamp "[is] unset, it will be set to the current time when emit() is called." (javadoc).

This does not seem to be consistent with the implementation of SdkLogRecordBuilder#emit (src) as it only provides a default value for the observed timestamp, not for the (event) timestamp.

Steps to reproduce

The following snippet produces a log entry that has an observed timestamp configured. The (event) timestamp is missing.

Logger logger = GlobalOpenTelemetry.get().getLogsBridge().get("some-instrumentation-scope");

Attributes attributes = Attributes.builder()
    .put(AttributeKey.stringKey("tenant-id"), "some-tenant-id")
    .build();

logger.logRecordBuilder()
    .setBody("some-message")
    .setSeverity(Severity.INFO)
    .setAllAttributes(attributes)
    .emit();
}

What did you expect to see?
The produced record should either include the (event) timestamp or the javadoc should not mention that the value is automatically populated.

What did you see instead?
(not applicable)

What version and what artifacts are you using?

• io.opentelemetry:opentelemetry-bom:1.57.0
• io.opentelemetry.javaagent:opentelemetry-javaagent:2.25.0

Environment
(not applicable)

Additional context
(not applicable)

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[jack-berg]

Good catch. To confirm, the behavior of the SDK appears to be correct since the relevant spec explicitly mentioned that observed timestamp should be set to the current time if not set, but makes no mention of the timestamp.

Looks like we never updated the javadoc after #5374.

So the correct course of action is to update the javadoc.

[inshining]

Hello, @jack-berg Can i try working on it?

[jack-berg]

Go for it @inshining