add changelog

CHANGELOG.md

@@ -59,3 +59,18 @@ release.
   ([#3355](https://github.com/open-telemetry/opentelemetry-specification/pull/3355))
 - Add `gcp.cloud_run.job.execution` and `gcp.cloud_run.job.task_id` resource
   attributes for GCP Cloud Run Jobs ([#3378](https://github.com/open-telemetry/opentelemetry-specification/pull/3378))
+- BREAKING: Add namespaces to JVM metric attributes ([#20](https://github.com/open-telemetry/semantic-conventions/pull/20)).
+  - Memory metric attribute renames
+    - Applies to metrics
+      - `metric.process.runtime.jvm.memory.usage`
+      - `metric.process.runtime.jvm.memory.init`
+      - `metric.process.runtime.jvm.memory.committed`
+      - `metric.process.runtime.jvm.memory.limit`
+      - `metric.process.runtime.jvm.memory.usage_after_last_gc`
+    - Rename `memory` to `memory.type`
+    - Rename `pool` to `memory.pool.name`
+  - Rename `process.runtime.jvm.gc.duration` metric attribute `gc` to `gc.name`
+  - Rename `process.runtime.jvm.gc.duration` metric attribute `action` to `gc.action`
+  - Rename `process.runtime.jvm.threads.count` metric attribute `daemon` to `thread.daemon`
+  - Rename `attributes.process.runtime.jvm.buffer` metric attribute `pool` to `buffer.pool.name`
+