Don't add empty headers on lambda completion

[amarziali]

What Does This Do

Adding empty headers is not supported by okHttp. This PR add guards around possibly empty values.

Guards from errors like:

java.lang.IllegalArgumentException
  at datadog.okhttp3.Headers.checkValue(Headers.java:272)
  at datadog.okhttp3.Headers$Builder.add(Headers.java:312)
  at datadog.okhttp3.Request$Builder.addHeader(Request.java:196)
  at datadog.trace.lambda.LambdaHandler.notifyEndInvocation(LambdaHandler.java:125)
  at datadog.trace.agent.core.CoreTracer.notifyExtensionEnd(CoreTracer.java:1248)

Motivation

Additional Notes

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Jira ticket: [PROJ-IDENT]

[dd-octo-sts]

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[dd-octo-sts]

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	13.92 s	14.06 s	[-2.4%; +0.3%] (no difference)
startup:insecure-bank:tracing:Agent	12.85 s	12.90 s	[-1.1%; +0.3%] (no difference)
startup:petclinic:appsec:Agent	16.38 s	16.44 s	[-1.5%; +0.8%] (no difference)
startup:petclinic:iast:Agent	16.49 s	16.70 s	[-2.4%; -0.1%] (maybe better)
startup:petclinic:profiling:Agent	16.54 s	16.71 s	[-2.6%; +0.6%] (no difference)
startup:petclinic:tracing:Agent	15.78 s	15.77 s	[-1.0%; +1.2%] (no difference)

Commit: 829151a0 · CI Pipeline · Benchmarking Platform UI

---

Load and DaCapo benchmarks can be triggered manually in the GitLab pipeline. Results will appear in the Benchmarking Platform UI after completion.

[dougqh]

I think a helper method that handles this might be a cleaner solution

[dd-octo-sts]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-06-03 17:44:24 UTC ℹ️ Start processing command /merge

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2026-06-03 17:44:28 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 1h (p90).

---

2026-06-03 18:15:13 UTC ⚠️ MergeQueue: This merge request build was cancelled

andrea.marziali@datadoghq.com cancelled this merge request build

[purple4reina]

+1 on Douglas's comment though

[amarziali]

I think a helper method that handles this might be a cleaner solution

I wanted to avoid to add more to Strings but it's true that I can add something to LambdaHandler indeed

[amarziali]

/merge -c

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-06-03 18:14:58 UTC ℹ️ Start processing command /merge -c

[dd-octo-sts]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-06-04 07:44:43 UTC ℹ️ Start processing command /merge

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2026-06-04 07:44:48 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 1h (p90).

---

2026-06-04 09:14:28 UTC ℹ️ MergeQueue: This merge request was merged