Fix incorrect throw of exception in global tracer assignment

tracing/providers/opentelemetry/src/main/java/io/helidon/tracing/providers/opentelemetry/OpenTelemetryTracerProvider.java

@@ -129,6 +129,7 @@ public Tracer global() {
     public void global(Tracer tracer) {
         if (tracer instanceof OpenTelemetryTracer ott) {
             globalTracer(ott);
+            return;
         }
         throw new IllegalArgumentException("Tracer must be an instance of Helidon OpenTelemetry tracer. "
                                                    + "Please use HelidonOpenTelemetry to create such instance");

tracing/providers/opentelemetry/src/test/java/io/helidon/tracing/providers/opentelemetry/TestGlobalTracerAssignment.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.tracing.providers.opentelemetry;
+
+import java.util.Map;
+
+import io.helidon.tracing.Tracer;
+
+import io.opentelemetry.api.OpenTelemetry;
+import org.junit.jupiter.api.Test;
+
+class TestGlobalTracerAssignment {
+
+    @Test
+    void assignGlobalTracer() {
+        OpenTelemetry openTelemetry = OpenTelemetry.noop();
+        io.opentelemetry.api.trace.Tracer otelTracer = openTelemetry.getTracer("testTracer");
+
+        Tracer.global(HelidonOpenTelemetry.create(openTelemetry, otelTracer, Map.of()));
+        // A bug in the Helidon OTel tracer provider caused an exception to be thrown even when the caller provides the correct
+        // type to Tracer.global(tracer). If we get here, the bug fix is working.
+    }
+}