feat(ibm-mq-metrics): report queue manager uptime (#2823)

[harshitt13]

Description:

Feature addition - This PR introduces a new metric to report the cumulative uptime of the queue manager in seconds, providing better visibility into queue manager restarts compared to the static heartbeat metric.

• Added ibm_mq.queue_manager.uptime metric (Gauge, seconds) calculating uptime from PCF attributes CMQCFC.MQCACF_Q_MGR_START_DATE and CMQCFC.MQCACF_Q_MGR_START_TIME.
• Eliminated timezone drift by securely anchoring the parsed IBM MQ local time to ZoneOffset.UTC.
• Enabled the new metric in the default configuration.
• Deprecated the existing heartbeat metric per the issue discussion, keeping it active with @SuppressWarnings during the transition period so users aren't immediately broken.

Existing Issue(s):

Fixes #2823

Testing:

• Updated QueueManagerMetricsCollectorTest to inject mock start dates/times into the PCF response and verify the new gauge emission.
• Created MessageBuddyTest to explicitly verify that the uptime calculation remains perfectly stable regardless of the collector host's underlying JVM default timezone.
• Executed ./gradlew :ibm-mq-metrics:generateWeaver and verified existing module tests pass cleanly.

Documentation:

• Updated model/metrics.yaml and config.yml to define and enable the new ibm_mq.queue_manager.uptime metric.
• Added standard Java @Deprecated annotations and Javadoc for the heartbeat metric.

Outstanding items:

• The heartbeat metric is currently deprecated but still emitting. It will need to be completely removed in a future major release.

[Copilot]

Pull request overview

Adds a new ibm.mq.queue_manager.uptime gauge that reports cumulative queue-manager uptime in seconds (derived from PCF MQCA_Q_MGR_START_DATE/MQCA_Q_MGR_START_TIME), and deprecates the existing ibm.mq.heartbeat metric in favor of it.

Changes:

• Adds Metrics.createIbmMqQueueManagerUptime, MetricsConfig.isIbmMqQueueManagerUptimeEnabled, a new MessageBuddy.queueManagerUptime helper, and emits the value in QueueManagerMetricsCollector.
• Marks Metrics.createIbmMqHeartbeat as @Deprecated and wraps its consumer in WmqMonitor with @SuppressWarnings("OtelDeprecatedApiUsage").
• Updates model/metrics.yaml with the new metric definition and a deprecation note on ibm.mq.heartbeat.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
ibm-mq-metrics/model/metrics.yaml	Declares the new uptime metric and notes deprecation of heartbeat.
ibm-mq-metrics/src/main/java/io/opentelemetry/ibm/mq/metrics/Metrics.java	Adds the uptime gauge factory and @Deprecated annotation on heartbeat.
ibm-mq-metrics/src/main/java/io/opentelemetry/ibm/mq/metrics/MetricsConfig.java	Adds an enable flag for the new metric.
ibm-mq-metrics/src/main/java/io/opentelemetry/ibm/mq/metricscollector/MessageBuddy.java	Parses PCF start date/time and computes uptime in seconds.
ibm-mq-metrics/src/main/java/io/opentelemetry/ibm/mq/metricscollector/QueueManagerMetricsCollector.java	Registers the gauge and emits the new metric inside the collection loop.
ibm-mq-metrics/src/main/java/io/opentelemetry/ibm/mq/WmqMonitor.java	Suppresses the deprecation warning for the still-active heartbeat gauge.

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