# Overview

Closes #6786

### Added

- Add exponential histogram support in
`go.opentelemetry.io/otel/exporters/prometheus`. (#6421)
- The `go.opentelemetry.io/otel/semconv/v1.31.0` package.
The package contains semantic conventions from the `v1.31.0` version of
the OpenTelemetry Semantic Conventions.
See the [migration documentation](./semconv/v1.31.0/MIGRATION.md) for
information on how to upgrade from
`go.opentelemetry.io/otel/semconv/v1.30.0`. (#6479)
- Add `Recording`, `Scope`, and `Record` types in
`go.opentelemetry.io/otel/log/logtest`. (#6507)
- Add `WithHTTPClient` option to configure the `http.Client` used by
`go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`.
(#6751)
- Add `WithHTTPClient` option to configure the `http.Client` used by
`go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp`.
(#6752)
- Add `WithHTTPClient` option to configure the `http.Client` used by
`go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#6688)
- Add `ValuesGetter` in `go.opentelemetry.io/otel/propagation`, a
`TextMapCarrier` that supports retrieving multiple values for a single
key. (#5973)
- Add `Values` method to `HeaderCarrier` to implement the new
`ValuesGetter` interface in `go.opentelemetry.io/otel/propagation`.
(#5973)
- Update `Baggage` in `go.opentelemetry.io/otel/propagation` to retrieve
multiple values for a key when the carrier implements `ValuesGetter`.
(#5973)
- Add `AssertEqual` function in `go.opentelemetry.io/otel/log/logtest`.
(#6662)
- The `go.opentelemetry.io/otel/semconv/v1.32.0` package.
The package contains semantic conventions from the `v1.32.0` version of
the OpenTelemetry Semantic Conventions.
See the [migration documentation](./semconv/v1.32.0/MIGRATION.md) for
information on how to upgrade from
`go.opentelemetry.io/otel/semconv/v1.31.0`(#6782)
- Add `Transform` option in `go.opentelemetry.io/otel/log/logtest`.
(#6794)
- Add `Desc` option in `go.opentelemetry.io/otel/log/logtest`. (#6796)

### Removed

- Drop support for [Go 1.22]. (#6381, #6418)
- Remove `Resource` field from `EnabledParameters` in
`go.opentelemetry.io/otel/sdk/log`. (#6494)
- Remove `RecordFactory` type from
`go.opentelemetry.io/otel/log/logtest`. (#6492)
- Remove `ScopeRecords`, `EmittedRecord`, and `RecordFactory` types from
`go.opentelemetry.io/otel/log/logtest`. (#6507)
- Remove `AssertRecordEqual` function in
`go.opentelemetry.io/otel/log/logtest`, use `AssertEqual` instead.
(#6662)

### Changed

- ⚠️ Update `github.com/prometheus/client_golang` to `v1.21.1`, which
changes the `NameValidationScheme` to `UTF8Validation`.
This allows metrics names to keep original delimiters (e.g. `.`), rather
than replacing with underscores.
This can be reverted by setting
`github.com/prometheus/common/model.NameValidationScheme` to
`LegacyValidation` in `github.com/prometheus/common/model`. (#6433)
- Initialize map with `len(keys)` in `NewAllowKeysFilter` and
`NewDenyKeysFilter` to avoid unnecessary allocations in
`go.opentelemetry.io/otel/attribute`. (#6455)
- `go.opentelemetry.io/otel/log/logtest` is now a separate Go module.
(#6465)
- `go.opentelemetry.io/otel/sdk/log/logtest` is now a separate Go
module. (#6466)
- `Recorder` in `go.opentelemetry.io/otel/log/logtest` no longer
separately stores records emitted by loggers with the same
instrumentation scope. (#6507)
- Improve performance of `BatchProcessor` in
`go.opentelemetry.io/otel/sdk/log` by not exporting when exporter cannot
accept more. (#6569, #6641)

### Deprecated

- Deprecate support for `model.LegacyValidation` for
`go.opentelemetry.io/otel/exporters/prometheus`. (#6449)

### Fixes

- Stop percent encoding header environment variables in
`go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc` and
`go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#6392)
- Ensure the `noopSpan.tracerProvider` method is not inlined in
`go.opentelemetry.io/otel/trace` so the `go.opentelemetry.io/auto`
instrumentation can instrument non-recording spans. (#6456)
- Use a `sync.Pool` instead of allocating `metricdata.ResourceMetrics`
in `go.opentelemetry.io/otel/exporters/prometheus`. (#6472)

---------

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
Co-authored-by: Robert Pająk <pellared@hotmail.com>