Add 'Contributing' message (#1108)

Co-authored-by: RoBorg <roborg@gmail.com>

Add scheme to collector endpoint on traces example (#913)

Add scheme to collector endpoint on traces example docker-composer file

doco updates for beta (#895)

Run exports with the `Context` the `SpanProcessor` was created in (#880)

* Run exports in spanprocessor construction context

* Resolve psalm issues

Fix OTLP GRPC example (#856)

Added B3Propagator for B3 Single Header (#691)

* Added B3Propagator Class to handle two configurations and storing debug flag in the returned context
* Updated B3Propagator extract according to the clarification in the specs; updated test cases

Add metrics implementation (#750)

* Add metrics implementation

* Apply cs-fixer

* Downgrade to php 7.4

* [TODO] Suppress phan for now

* Add basic example

* [TODO] Remove outdated prometheus example for now

* Add otlp metric converter

* Add metric stream tests

* Downgrade to php 7.4 - fix asynchronous counter instrument type

* Add missing psalm-suppress annotations

* Add `ext-gmp` to composer suggest

* Fix `Sdk` -> `SDK`

* Remove `_bridge.php`

* Add array typehints

* Add `Interface` suffix to interfaces

* Add aggregation / attribute processor / staleness handler tests

* Apply rector

* Simplify filtered attribute processor

* Move instrument deduplication to meter

Allows removing view registry dependency from `MetricFactory`.
Should ideally turn of staleness handling for asynchronous instruments with permanently registered callbacks (drop all `::onStale()` callbacks and prevent addition of new callbacks).

* Allow injecting metric factory

* Release `::onStale()` callbacks if permanent observer callback registered

* Add `MultiObserver` tests

* Add php-doc for exporter temporality

* Resolve phan issues

* Add note about forward compatibility

* Add exemplar tests

* Remove special handling for callbacks being registered multiple times

Was mainly a side-effect of using `spl_object_id()`; lead to inconsistent behavior between providing same and identical callbacks; reverting back to incrementing index, keyspace is large enough.

* Add basic `Meter` / `MeterProvider` tests

* Add view `SelectionCriteria` tests

* Allow `MetricReader`s to configure default aggregation

- move default aggregation handling to metric reader / metric exporter
- move view registration to meter provider constructor
- move exemplar reservoir creation to aggregation to support user implementations
- remove `AttributeProcessor` from view as baggage access was dropped from spec
- deduplicate metric streams

* Add support for weakening `$this` reference of asynchronous callbacks

* Minor improvements

- add missing `Interface` suffix
- move callback destructors to metric observer to not detach if meter and meter provider are out of scope
- simplify `::viewRegistrationRequests()` by readding fallback view

* Add OTLP metric exporter

* Log export failure

* Minor improvements

- rename `MetricObserver::weakMap()` to `::destructors()` to better reflect usage`
- move `ReferenceCounter::acquire()` call to corresponding `MetricObserver::observe()` call for consistency
- cache instrumentation scope id in `Meter` to avoid repeated calls to `serialize()`
- remove obsolete instrument type check from `ViewProjection`, leftover from supporting aggregation per type

* Suppress `PhanAccessMethodInternal` due to being too strict for our usecase

* Add workaround for observer segfault if destruct is initiated by `WeakMap` key going out of scope

* Mark internal classes as internal

* Add in-memory and stream exporter

* Add metric converter test

* Add metric observer tests

* Add view registry tests

* Add metric reader tests

* Improve stream test coverage

* Improve meter test coverage

* Apply rector

* Add delayed staleness handler

Tracer references tests (#759)

* adding tests for tracer provider behaviour
a recent bug highlighted that if there is no reference to a tracer provider, then the shared state will shutdown, even if that shared state is being used by active tracers. Adding a phpdoc comment explaining this behavior, and some tests to demonstrate it

* moving tests into integration

* removing accidental covers annotation

Bump guzzlehttp/guzzle in /examples/distributed-tracing/src (#722)

Bumps [guzzlehttp/guzzle](https://github.com/guzzle/guzzle) from 7.4.4 to 7.4.5.
- [Release notes](https://github.com/guzzle/guzzle/releases)
- [Changelog](https://github.com/guzzle/guzzle/blob/master/CHANGELOG.md)
- [Commits](guzzle/guzzle@7.4.4...7.4.5)

---
updated-dependencies:
- dependency-name: guzzlehttp/guzzle
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Added B3MultiPropagater (#680)

* Added B3MultiPropagater

* Added static self and removed case insensitive getter function

* Added unit tests for B3MultiPropagator class

* Refactored B3MultiPropagator and added tests in B3MultiPropagatorTest

* Added description for B3MultiPropagator