Gardening: Mark CbTracing.newSpan() as used by Spring Data Couchbase

Change-Id: I26bb25b57810aa881abd00ae7d444d913c1524df
Reviewed-on: https://review.couchbase.org/c/couchbase-jvm-clients/+/213437
Tested-by: Build Bot <[email protected]>
Reviewed-by: Graham Pople <[email protected]>

Author: dnault

core-io/src/main/java/com/couchbase/client/core/cnc/CbTracing.java

@@ -18,6 +18,7 @@
 
 import com.couchbase.client.core.CoreContext;
 import com.couchbase.client.core.annotation.Stability;
+import com.couchbase.client.core.annotation.UsedBy;
 import com.couchbase.client.core.cnc.tracing.NoopRequestSpan;
 import com.couchbase.client.core.cnc.tracing.NoopRequestTracer;
 import com.couchbase.client.core.cnc.tracing.ThresholdLoggingTracer;
@@ -27,6 +28,7 @@
 import java.util.EnumMap;
 import java.util.Map;
 
+import static com.couchbase.client.core.annotation.UsedBy.Project.SPRING_DATA_COUCHBASE;
 import static java.util.Collections.unmodifiableMap;
 
 @Stability.Internal
@@ -61,6 +63,7 @@ public static boolean isInternalSpan(final RequestSpan span) {
    * Returns a new span with the `db.system` attribute set to `couchbase`.
    * @param parent (nullable)
    */
+  @UsedBy(SPRING_DATA_COUCHBASE)
   public static RequestSpan newSpan(CoreContext coreContext, String spanName, RequestSpan parent) {
     return newSpan(coreContext.environment().requestTracer(), spanName, parent);
   }