Update otel4s to 0.15.0 and otel4s-sdk to 0.16.0 (#2772)

Before submitting pull request:
- [x] Check if the project compiles by running `sbt compile`
- [x] Verify docs compilation by running `sbt compileDocs`
- [x] Check if tests pass by running `sbt test`
- [x] Format code by running `sbt scalafmt`

Author: iRevive

build.sbt

@@ -170,7 +170,8 @@ val osLibVersion = "0.11.4"
 val tethysVersion = "0.29.7"
 val openTelemetryVersion = "1.58.0"
 val openTelemetrySemconvVersion = "1.37.0"
-val otel4s = "0.14.0"
+val otel4s = "0.15.0"
+val otel4sSdk = "0.16.0"
 val slf4jVersion = "1.7.36"
 
 val compileAndTest = "compile->compile;test->test"
@@ -957,7 +958,7 @@ lazy val otel4sMetricsBackend = (projectMatrix in file("observability/otel4s-met
       "org.typelevel" %%% "otel4s-core-metrics" % otel4s,
       "org.typelevel" %%% "otel4s-semconv" % otel4s,
       "org.typelevel" %%% "otel4s-semconv-metrics-experimental" % otel4s % Test,
-      "org.typelevel" %%% "otel4s-sdk-metrics-testkit" % otel4s % Test
+      "org.typelevel" %%% "otel4s-sdk-metrics-testkit" % otel4sSdk % Test
     )
   )
   .jvmPlatform(scalaVersions = scala2_13And3, settings = commonJvmSettings)
@@ -971,7 +972,7 @@ lazy val otel4sTracingBackend = (projectMatrix in file("observability/otel4s-tra
     libraryDependencies ++= Seq(
       "org.typelevel" %%% "otel4s-core-trace" % otel4s,
       "org.typelevel" %%% "otel4s-semconv" % otel4s,
-      "org.typelevel" %%% "otel4s-sdk-trace-testkit" % otel4s % Test,
+      "org.typelevel" %%% "otel4s-sdk-trace-testkit" % otel4sSdk % Test,
       "org.typelevel" %%% "cats-effect-testkit" % catsEffect_3_version % Test
     )
   )

observability/otel4s-tracing-backend/src/main/scala/sttp/client4/opentelemetry/otel4s/Otel4sTracingBackend.scala

@@ -54,35 +54,35 @@ object Otel4sTracingBackend {
       delegate: Backend[F],
       config: Otel4sTracingConfig
   ): F[Backend[F]] =
-    usingMeter { implicit tracer: Tracer[F] =>
+    usingTracer { implicit tracer: Tracer[F] =>
       FollowRedirectsBackend(new Otel4sTracingBackend(delegate, config) with Backend[F])
     }
 
   def apply[F[_]: MonadCancelThrow: TracerProvider](
       delegate: WebSocketBackend[F],
       config: Otel4sTracingConfig
   ): F[WebSocketBackend[F]] =
-    usingMeter { implicit tracer: Tracer[F] =>
+    usingTracer { implicit tracer: Tracer[F] =>
       FollowRedirectsBackend(new Otel4sTracingBackend(delegate, config) with WebSocketBackend[F])
     }
 
   def apply[F[_]: MonadCancelThrow: TracerProvider, S](
       delegate: StreamBackend[F, S],
       config: Otel4sTracingConfig
   ): F[StreamBackend[F, S]] =
-    usingMeter { implicit tracer: Tracer[F] =>
+    usingTracer { implicit tracer: Tracer[F] =>
       FollowRedirectsBackend(new Otel4sTracingBackend(delegate, config) with StreamBackend[F, S])
     }
 
   def apply[F[_]: MonadCancelThrow: TracerProvider, S](
       delegate: WebSocketStreamBackend[F, S],
       config: Otel4sTracingConfig
   ): F[WebSocketStreamBackend[F, S]] =
-    usingMeter { implicit tracer: Tracer[F] =>
+    usingTracer { implicit tracer: Tracer[F] =>
       FollowRedirectsBackend(new Otel4sTracingBackend(delegate, config) with WebSocketStreamBackend[F, S])
     }
 
-  private def usingMeter[F[_]: MonadCancelThrow: TracerProvider, A](f: Tracer[F] => A): F[A] =
+  private def usingTracer[F[_]: MonadCancelThrow: TracerProvider, A](f: Tracer[F] => A): F[A] =
     for {
       tracer <- TracerProvider[F].tracer("sttp-client4").withVersion("1.0.0").get
     } yield f(tracer)

observability/otel4s-tracing-backend/src/test/scala/sttp/client4/opentelemetry/otel4s/Otel4sTracingBackendTest.scala

@@ -43,7 +43,9 @@ class Otel4sTracingBackendTest extends AsyncFreeSpec with Matchers {
   "Otel4sTracingBackend" - {
     "should add tracing headers to the request" in {
       TracesTestkit
-        .inMemory[IO](_.addTextMapPropagators(W3CTraceContextPropagator.default))
+        .builder[IO]
+        .addTracerProviderCustomizer(_.addTextMapPropagators(W3CTraceContextPropagator.default))
+        .build
         .use { testkit =>
           implicit val tracerProvider: TracerProvider[IO] = testkit.tracerProvider
 
@@ -65,7 +67,9 @@ class Otel4sTracingBackendTest extends AsyncFreeSpec with Matchers {
 
     "should record request/response-specific attributes: 200 OK response" in {
       TracesTestkit
-        .inMemory[IO](_.addTextMapPropagators(W3CTraceContextPropagator.default))
+        .builder[IO]
+        .addTracerProviderCustomizer(_.addTextMapPropagators(W3CTraceContextPropagator.default))
+        .build
         .use { testkit =>
           implicit val tracerProvider: TracerProvider[IO] = testkit.tracerProvider
 
@@ -107,7 +111,9 @@ class Otel4sTracingBackendTest extends AsyncFreeSpec with Matchers {
 
     "should record request/response-specific attributes: 400 BadRequest response" in {
       TracesTestkit
-        .inMemory[IO](_.addTextMapPropagators(W3CTraceContextPropagator.default))
+        .builder[IO]
+        .addTracerProviderCustomizer(_.addTextMapPropagators(W3CTraceContextPropagator.default))
+        .build
         .use { testkit =>
           implicit val tracerProvider: TracerProvider[IO] = testkit.tracerProvider
 
@@ -152,7 +158,9 @@ class Otel4sTracingBackendTest extends AsyncFreeSpec with Matchers {
       TestControl
         .executeEmbed {
           TracesTestkit
-            .inMemory[IO](_.addTextMapPropagators(W3CTraceContextPropagator.default))
+            .builder[IO]
+            .addTracerProviderCustomizer(_.addTextMapPropagators(W3CTraceContextPropagator.default))
+            .build
             .use { testkit =>
               implicit val tracerProvider: TracerProvider[IO] = testkit.tracerProvider