GA Readiness for Metrics Release - Spec Compliance Check

[alolita]

We are preparing a GA release for metrics. As of June 5 2025, the following items need to be verified in the implementation or need to be itemized as features to be implemented in a subsequent release after the GA release.

The features reviewed and listed in this issue are based on the OTel Spec Compliance Matrix Metrics section. The spec can be found at https://github.com/open-telemetry/opentelemetry-specification/blob/main/spec-compliance-matrix.md

1. The following features need to be verified:

• Invalid meter name - needs to be verified
• A valid instrument MUST be created and warning SHOULD be emitted when multiple instruments are registered under the same Meter using the same name. - Warning needs to be verified
• Duplicate instrument registration name conflicts are resolved by using the first-seen for the stream name. - Needs to be verified
• Instrument names conform to the specified syntax. - Needs to be verified
• Instrument descriptions conform to the specified syntax.- Needs to be verified
• Instrument supports the advisory ExplicitBucketBoundaries parameter. - Needs to be verified https://opentelemetry.io/docs/specs/otel/metrics/api/#instrument-advisory-parameters
• The MeterProvider provides methods to update the configuration - needs to be verified
• There is a way to register Views with a MeterProvider. - needs to be verified
• The ExponentialBucketHistogram aggregation is available. - needs to be verified
• The metrics Exporter export function can not be called concurrently from the same Exporter instance. - needs to be verified
• The metrics Exporter ForceFlush can inform the caller whether it succeeded, failed or timed out. - Need to verify timeout
• The metrics SDK supports SDK-wide exemplar filter configuration - needs to be verified
• The metrics SDK provides an AlignedHistogramBucketExemplarReservoir that is used by default for ExplicitBucketHistogram aggregation. - Needs to be verified
• A metric Producer accepts an optional metric Filter - - Needs to be verified
• The metric Reader implementation supports registering metric Filter and passing them its registered metric Producers - - Needs to be verified
• The metric SDK's metric Producer implementations uses the metric Filter - - Needs to be verified

2. The following features are not supported yet. These could be supported in a minor release after GA.

• Metric SDK implements cardinality limit - may not be supported yet - there is a open issue - https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#cardinality-limits default of 200 could be used
• Metric SDK supports configuring cardinality limit at MeterReader level - not implemented yet
• Metric SDK supports configuring cardinality limit per metric (using Views) - not implemented yet

3. Ignore optional call outs for now.