### Added

- Add `go.opentelemetry.io/otel/sdk/metric/exemplar` package which
includes `Exemplar`, `Filter`, `TraceBasedFilter`, `AlwaysOnFilter`,
`HistogramReservoir`, `FixedSizeReservoir`, `Reservoir`, `Value` and
`ValueType` types. These will be used for configuring the exemplar
reservoir for the metrics sdk. (#5747, #5862)
- Add `WithExportBufferSize` option to log batch processor.(#5877)

### Changed

- Enable exemplars by default in `go.opentelemetry.io/otel/sdk/metric`.
Exemplars can be disabled by setting
`OTEL_METRICS_EXEMPLAR_FILTER=always_off` (#5778)
- `Logger.Enabled` in `go.opentelemetry.io/otel/log` now accepts a newly
introduced `EnabledParameters` type instead of `Record`. (#5791)
- `FilterProcessor.Enabled` in
`go.opentelemetry.io/otel/sdk/log/internal/x` now accepts
`EnabledParameters` instead of `Record`. (#5791)
- The `Record` type in `go.opentelemetry.io/otel/log` is no longer
comparable. (#5847)
- Performance improvements for the trace SDK `SetAttributes` method in
`Span`. (#5864)
- Reduce memory allocations for the `Event` and `Link` lists in `Span`.
(#5858)
- Performance improvements for the trace SDK `AddEvent`, `AddLink`,
`RecordError` and `End` methods in `Span`. (#5874)

### Deprecated

- Deprecate all examples under `go.opentelemetry.io/otel/example` as
they are moved to [Contrib
repository](https://github.com/open-telemetry/opentelemetry-go-contrib/tree/main/examples).
(#5854)

### Fixed

- The race condition for multiple `FixedSize` exemplar reservoirs
identified in #5814 is resolved. (#5819)
- Fix log records duplication in case of heterogeneous resource
attributes by correctly mapping each log record to it's resource and
scope. (#5803)
- Fix timer channel drain to avoid hanging on Go 1.23. (#5868)
- Fix delegation for global meter providers, and panic when calling
otel.SetMeterProvider. (#5827)
- Change the `reflect.TypeOf` to use a nil pointer to not allocate on
the heap unless necessary. (#5827)