fixes open-telemetry#1600 (open-telemetry#1603)

Author: smaddock

src/Contrib/Otlp/OtlpHttpTransportFactory.php

@@ -4,9 +4,9 @@
 
 namespace OpenTelemetry\Contrib\Otlp;
 
-use OpenTelemetry\SDK\Common\Export\Http\PsrTransport;
 use OpenTelemetry\SDK\Common\Export\Http\PsrTransportFactory;
 use OpenTelemetry\SDK\Common\Export\TransportFactoryInterface;
+use OpenTelemetry\SDK\Common\Export\TransportInterface;
 
 class OtlpHttpTransportFactory implements TransportFactoryInterface
 {
@@ -23,7 +23,7 @@ public function create(
         ?string $cacert = null,
         ?string $cert = null,
         ?string $key = null,
-    ): PsrTransport {
+    ): TransportInterface {
         if ($compression === self::DEFAULT_COMPRESSION) {
             $compression = null;
         }

src/SDK/Common/Export/Http/PsrTransportFactory.php

@@ -10,6 +10,7 @@
 use Http\Discovery\Psr18ClientDiscovery;
 use InvalidArgumentException;
 use OpenTelemetry\SDK\Common\Export\TransportFactoryInterface;
+use OpenTelemetry\SDK\Common\Export\TransportInterface;
 use OpenTelemetry\SDK\Common\Http\Psr\Client\Discovery;
 use Psr\Http\Client\ClientInterface;
 use Psr\Http\Message\RequestFactoryInterface;
@@ -38,7 +39,7 @@ public function create(
         ?string $cacert = null,
         ?string $cert = null,
         ?string $key = null,
-    ): PsrTransport {
+    ): TransportInterface {
         if (!filter_var($endpoint, FILTER_VALIDATE_URL)) {
             throw new InvalidArgumentException(sprintf('Invalid endpoint url "%s"', $endpoint));
         }