feat(bigquery observability): add version attribute to span tracing (#12132)

This PR adds the gcp.client.version attribute to the span trace. It
follows the general java guidance on retrieving version at runtime, by
creating a Version.java file that stores the current version and is
updated via release-please. See gapic version
[here](googleapis/sdk-platform-java@67a2ecb#diff-65705b9eaa79c4e543f0325d909aa60704b3e1ae06deba47ab2690f69810a69d).

[Example trace with
attribute](https://screenshot.googleplex.com/3v8NTeXSUrNipuB.png).

There is a [separate
task](#12130) to
update release-please to handle updating this file.

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: ldetmer

java-bigquery/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/telemetry/BigQueryTelemetryTracer.java

@@ -70,8 +70,8 @@ public static void addCommonAttributeToSpan(Span span) {
     span.setAttribute(GCP_CLIENT_SERVICE, BQ_GCP_CLIENT_SERVICE)
         .setAttribute(GCP_CLIENT_REPO, BQ_GCP_CLIENT_REPO)
         .setAttribute(GCP_CLIENT_ARTIFACT, BQ_GCP_CLIENT_ARTIFACT)
-        .setAttribute(GCP_CLIENT_LANGUAGE, BQ_GCP_CLIENT_LANGUAGE);
-    // TODO: add version
+        .setAttribute(GCP_CLIENT_LANGUAGE, BQ_GCP_CLIENT_LANGUAGE)
+        .setAttribute(GCP_CLIENT_VERSION, Version.VERSION);
   }
 
   /**

java-bigquery/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/telemetry/Version.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * 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 com.google.cloud.bigquery.telemetry;
+
+import com.google.api.core.InternalApi;
+
+/**
+ * Version class defines current google-cloud-bigquery artifact version to be referenced at runtime
+ * for telemetry purposes.
+ */
+@InternalApi("For internal use only")
+final class Version {
+  // {x-version-update-start:google-cloud-bigquery:current}
+  static final String VERSION = "2.63.0-SNAPSHOT";
+  // {x-version-update-end}
+}

java-bigquery/google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/telemetry/BigQueryTelemetryTracerTest.java

@@ -164,6 +164,30 @@ public void testAddExceptionToSpan_NoMessage() {
         "CLIENT_UNKNOWN_ERROR", spanData.getAttributes().get(BigQueryTelemetryTracer.ERROR_TYPE));
   }
 
+  @Test
+  public void testAddCommonAttributeToSpan() {
+    BigQueryTelemetryTracer.addCommonAttributeToSpan(span);
+    span.end();
+
+    List<SpanData> spans = spanExporter.getFinishedSpanItems();
+    SpanData spanData = spans.get(0);
+
+    assertEquals(
+        BigQueryTelemetryTracer.BQ_GCP_CLIENT_SERVICE,
+        spanData.getAttributes().get(BigQueryTelemetryTracer.GCP_CLIENT_SERVICE));
+    assertEquals(
+        BigQueryTelemetryTracer.BQ_GCP_CLIENT_REPO,
+        spanData.getAttributes().get(BigQueryTelemetryTracer.GCP_CLIENT_REPO));
+    assertEquals(
+        BigQueryTelemetryTracer.BQ_GCP_CLIENT_ARTIFACT,
+        spanData.getAttributes().get(BigQueryTelemetryTracer.GCP_CLIENT_ARTIFACT));
+    assertEquals(
+        BigQueryTelemetryTracer.BQ_GCP_CLIENT_LANGUAGE,
+        spanData.getAttributes().get(BigQueryTelemetryTracer.GCP_CLIENT_LANGUAGE));
+    assertEquals(
+        Version.VERSION, spanData.getAttributes().get(BigQueryTelemetryTracer.GCP_CLIENT_VERSION));
+  }
+
   private GoogleJsonResponseException createException(
       String highLevelStatusCode, String errorMessage, String detailedErrorMessage, String reason) {
     GoogleJsonError googleJsonError = null;

java-bigquery/google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/telemetry/HttpTracingRequestInitializerTest.java

@@ -365,6 +365,8 @@ private void closeAndVerifySpanData(
     assertEquals(
         responseCode,
         span.getAttributes().get(HttpTracingRequestInitializer.HTTP_RESPONSE_STATUS_CODE));
+    assertEquals(
+        Version.VERSION, span.getAttributes().get(BigQueryTelemetryTracer.GCP_CLIENT_VERSION));
     assertEquals(
         method, span.getAttributes().get(HttpTracingRequestInitializer.HTTP_REQUEST_METHOD));
     if (requestBodySize >= 0) {