Add Micrometer metrics integration to OJP JDBC driver and Spring Boot starter

[Copilot]

OJP had OpenTelemetry metrics on the server side only — no client-side instrumentation and no Micrometer support for Spring Boot apps.

Driver-side metrics SPI (ojp-jdbc-driver)

Introduces a zero-coupling metrics abstraction so the driver never imports Micrometer:

• OjpDriverMetrics — interface with hooks: onConnectionCreated/Failed/Closed, onStatementExecuted(ms), onStatementFailed
• NoOpOjpDriverMetrics — singleton no-op default (zero overhead when no integration is active)
• OjpDriverMetricsHolder — volatile global holder; integrations call OjpDriverMetricsHolder.set(impl) at startup
• OjpMetricsIterator — wraps the server-streaming gRPC query iterator so timing/errors are recorded across the full result-stream lifetime, not just at RPC initiation

Hooks wired into:

Site	Event
Driver.connect()	onConnectionCreated / onConnectionFailed
Connection.close()	onConnectionClosed
StatementServiceGrpcClient.executeUpdate()	onStatementExecuted(ms) / onStatementFailed
StatementServiceGrpcClient.executeQuery()	delegated to OjpMetricsIterator

Micrometer auto-configuration (spring-boot-starter-ojp)

• OjpMicrometerDriverMetrics — OjpDriverMetrics impl backed by a MeterRegistry
• OjpMicrometerAutoConfiguration — activates only when @ConditionalOnBean(MeterRegistry.class) + OJP URL present; wires the impl into OjpDriverMetricsHolder

Activating is zero-config when spring-boot-starter-actuator is on the classpath. To disable:

@SpringBootApplication(exclude = OjpMicrometerAutoConfiguration.class)

Meters exposed

Meter	Type
ojp.driver.connections.created	Counter
ojp.driver.connections.failed	Counter
ojp.driver.connections.closed	Counter
ojp.driver.connections.active	Gauge
ojp.driver.statements.executed	Counter
ojp.driver.statements.failed	Counter
ojp.driver.statements.execution.time	Distribution Summary (ms)

All metrics auto-export to any configured Micrometer backend (Prometheus, Datadog, InfluxDB, etc.) without additional config. micrometer-core is declared optional so it does not become a transitive dependency.

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[sonarqubecloud]

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud