OpenTelemetry Collector 0.129.0 release notes

exporterhelper: Remove deprecated sending_queue::blocking options, use sending_queue::block_on_overflow. (#13211)

mdatagen: Taught mdatagen to print the go list stderr output on failures, and to run go list where the metadata file is. (#13205)
service: Support setting sampler and limits under service::telemetry::traces (#13201) This allows users to enable sampling and set span limits on internal Collector traces using the OpenTelemetry SDK declarative configuration.
pdata/pprofile: Add new helper methods FromLocationIndices and PutLocation to read and modify the content of locations. (#13150)
exporterhelper: Preserve request span context and client information in the persistent queue. (#11740, #13220, #13232) It allows internal collector spans and client information to propagate through the persistent queue used by the exporters. The same way as it's done for the in-memory queue. Currently, it is behind the exporter.PersistRequestContext feature gate, which can be enabled by adding --feature-gates=exporter.PersistRequestContext to the collector command line. An exporter buffer stored by a previous version of the collector (or by a collector with the feature gate disabled) can be read by a newer collector with the feature enabled. However, the reverse is not supported: a buffer stored by a newer collector with the feature enabled cannot be read by an older collector (or by a collector with the feature gate disabled).

pdata: Fix copying of optional fields when the source is unset. (#13268)
service: Only allocate one set of internal log sampling counters (#13014) The case where logs are only exported to stdout was fixed in v0.126.0; this new fix also covers the case where logs are exported through OTLP.

semconv: Removing deprecated semconv package (#13071)
configgrpc,confighttp: Unify return type of NewDefault*Config functions to return a struct instead of a pointer. (#13169)
exporterhelper: QueueBatchEncoding interface is changed to support marshaling and unmarshaling of request context. (#13188)

pdata/pprofile: Introduce Equal method on the Mapping type (#13197)
configoptional: Make unmarshaling into None[T] work the same as unmarshaling into (*T)(nil). (#13168)
configoptional: Add a confmap.Marshaler implementation for configoptional.Optional (#13196)
pdata/pprofile: Introduce Equal methods on the Line and Location types (#13150)
pdata/pprofile: Add new helper method SetMapping to set a new mapping on a location. (#13197)

confmap: Distinguish between empty and nil values when marshaling confmap.Conf structs. (#13196)