Fix NPE in DatabaseClientDecorator when JDBC connection has no db type

[dougqh]

What Does This Do

Guards DatabaseClientDecorator.processDatabaseType() and dbService() against a null dbType, instead of letting them NPE.

CACHE.computeIfAbsent(dbType, NamingEntry::new) returns null for a null key without invoking the producer (FixedSizeCache.computeIfAbsent, internal-api/.../FixedSizeCache.java:71-73). When dbType is null — e.g. JDBCDecorator.onConnection passing a DBInfo.getType() that couldn't be determined — the returned NamingEntry was dereferenced immediately afterward, throwing an NPE inside tracer instrumentation instead of degrading gracefully.

• processDatabaseType/dbService: check dbType == null up front and return early, rather than inferring the null case from the cache's return value.
• Added DatabaseClientDecoratorNullDbTypeTest covering both methods with a null dbType.

Motivation

Fixes a NullPointerException reported in Error Tracking (issue, 1300+ occurrences, first seen 2026-02-16, service mainframe-gateway via JDBC instrumentation):

java.lang.NullPointerException
  at DatabaseClientDecorator$NamingEntry.access$000(DatabaseClientDecorator.java:25)
  at DatabaseClientDecorator.processDatabaseType(DatabaseClientDecorator.java:148)
  at JDBCDecorator.onConnection(JDBCDecorator.java:158)

Additional Notes

/techdebt and /perf-review both came back clean: no duplication/complexity concerns, and the null-guards are a strict improvement on the previously-crashing path with no added cost on the normal path.

🤖 Generated with Claude Code

Contributor Checklist

• Format the title according to the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any other useful labels
• Avoid using close, fix, or any linking keywords when referencing an issue
• Update the CODEOWNERS file on source file addition, migration, or deletion
• Update public documentation with any new configuration flags or behaviors
• Once approved, use merge queue to merge the PR

Jira ticket: [PROJ-IDENT]

[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	13.96 s	13.86 s	[-0.2%; +1.5%] (no difference)
startup:insecure-bank:tracing:Agent	12.89 s	12.99 s	[-1.7%; +0.1%] (no difference)
startup:petclinic:appsec:Agent	17.00 s	16.88 s	[-0.2%; +1.5%] (no difference)
startup:petclinic:iast:Agent	16.94 s	16.91 s	[-0.7%; +0.9%] (no difference)
startup:petclinic:profiling:Agent	16.62 s	16.78 s	[-2.0%; +0.0%] (no difference)
startup:petclinic:sca:Agent	16.87 s	16.65 s	[+0.4%; +2.3%] (maybe worse)
startup:petclinic:tracing:Agent	16.06 s	15.99 s	[-0.6%; +1.4%] (no difference)

Commit: 0dd0abed · CI Pipeline · Benchmarking Platform UI

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[datadog-datadog-prod-us1-2]

More details

The null guards prevent both null dereferences. They keep the existing behavior for non-null database types.

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