Support Baggage propagation to the Instana propagator

Author: HeenaBansal20

src/Propagation/Instana/README.md

@@ -1,6 +1,6 @@
 OpenTelemetry Instana Propagator
 
-The OpenTelemetry Propagator for Instana provides HTTP header propagation for systems that are using IBM Observability by Instana.
+The OpenTelemetry Propagator for Instana provides HTTP header propagation and Baggage propagation for systems that are using IBM Observability by Instana.
 This propagator translates the Instana trace correlation headers (`X-INSTANA-T/X-INSTANA-S/X-INSTANA-L`) into the OpenTelemetry `SpanContext`, and vice versa.
 It does not handle `TraceState`.
 
@@ -14,10 +14,10 @@ composer require open-telemetry/opentelemetry-propagation-instana
 ## Usage
 
 ```
-$propagator = InstanaMultiPropagator::getInstance();
+$propagator = InstanaPropagator::getInstance();
 ```
 
-Both of the above have extract and inject methods available to extract and inject respectively into the header.
+Both of the above have extract and inject methods available to extract and inject respectively into the header. 
 
 ## Propagator Details
 

src/Propagation/Instana/_register.php

@@ -1,13 +1,14 @@
 <?php
 
 declare(strict_types=1);
-use OpenTelemetry\Contrib\Propagation\Instana\InstanaMultiPropagator;
+use OpenTelemetry\Contrib\Propagation\Instana\InstanaPropagator;
 use OpenTelemetry\SDK\Registry;
 
 if (!class_exists(Registry::class)) {
     return;
 }
+
 Registry::registerTextMapPropagator(
     'instana',
-    InstanaMultiPropagator::getInstance()
+    InstanaPropagator::getInstance()
 );

src/Propagation/Instana/src/InstanaMultiPropagator.php renamed to src/Propagation/Instana/src/InstanaContextPropagator.php

@@ -21,7 +21,7 @@
  * "instana" http headers used for trace context propagation across service
  * boundaries.
  */
-final class InstanaMultiPropagator implements TextMapPropagatorInterface
+final class InstanaContextPropagator implements TextMapPropagatorInterface
 {
     /**
      * The  X-INSTANA-T header is required and is encoded as 32 lower-hex characters.

src/Propagation/Instana/src/InstanaPropagator.php

@@ -0,0 +1,75 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Contrib\Propagation\Instana;
+
+use OpenTelemetry\API\Baggage\Propagation\BaggagePropagator;
+use OpenTelemetry\Context\ContextInterface;
+use OpenTelemetry\Context\Propagation\PropagationGetterInterface;
+use OpenTelemetry\Context\Propagation\PropagationSetterInterface;
+use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
+
+class InstanaPropagator implements TextMapPropagatorInterface
+{
+    /** @var TextMapPropagatorInterface[] */
+    private array $propagators;
+
+    private static ?self $instance = null;
+
+    public function __construct(array $propagators)
+    {
+        $this->propagators = $propagators;
+    }
+
+    public static function getInstance(): self
+    {
+        if (null === self::$instance) {
+            // Create propagator instances
+            $instanaPropagator =  InstanaContextPropagator::getInstance();
+            $baggagePropagator = new BaggagePropagator();
+            self::$instance = new self([$instanaPropagator, $baggagePropagator]);
+        }
+
+        return self::$instance;
+    }
+    
+    /**
+    * @suppress PhanUndeclaredClassAttribute
+    */
+    #[\Override]
+    public function fields(): array
+    {
+        $fields = [];
+        foreach ($this->propagators as $propagator) {
+            $fields = array_merge($fields, $propagator->fields());
+        }
+
+        return array_values(array_unique($fields));
+    }
+
+    /**
+     * @suppress PhanUndeclaredClassAttribute
+     */
+    #[\Override]
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
+    {
+        foreach ($this->propagators as $propagator) {
+            $propagator->inject($carrier, $setter, $context);
+        }
+    }
+    
+    /**
+     * @suppress PhanUndeclaredClassAttribute
+     */
+    #[\Override]
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
+    {
+        
+        foreach ($this->propagators as $propagator) {
+            $context = $propagator->extract($carrier, $getter, $context);
+        }
+        
+        return $context;
+    }
+}