server(alarms): honor ExcludeAttributes GR-only contract; warn on empty config-only watch-list

src/ZB.MOM.WW.MxGateway.Server/Alarms/AlarmWatchListResolver.cs

@@ -87,12 +87,19 @@ public sealed class AlarmWatchListResolver : IAlarmWatchListResolver
             ordered.Add((include, DeriveSourceObject(include)));
         }
 
-        // Remove excluded references (case-insensitive). Excludes are rare, so a
-        // per-entry lookup against a small set is fine.
-        HashSet<string> excluded = new(discovery.ExcludeAttributes, StringComparer.OrdinalIgnoreCase);
-        if (excluded.Count > 0)
+        // Remove excluded references (case-insensitive), but only when GR discovery
+        // is active. ExcludeAttributes is documented as "Ignored when
+        // UseGalaxyRepository is false" (AlarmDiscoveryOptions.ExcludeAttributes).
+        // Whitespace-only entries are skipped, consistent with the include guard above.
+        if (discovery.UseGalaxyRepository)
         {
-            ordered.RemoveAll(e => excluded.Contains(e.Reference));
+            HashSet<string> excluded = new(
+                discovery.ExcludeAttributes.Where(e => !string.IsNullOrWhiteSpace(e)),
+                StringComparer.OrdinalIgnoreCase);
+            if (excluded.Count > 0)
+            {
+                ordered.RemoveAll(e => excluded.Contains(e.Reference));
+            }
         }
 
         // 2. Resolve subtag names with safe fallbacks.
@@ -123,13 +130,16 @@ public sealed class AlarmWatchListResolver : IAlarmWatchListResolver
             });
         }
 
-        // 5. Report the resolved count; warn if subtag mode would cover nothing.
-        if (targets.Count == 0 && discovery.UseGalaxyRepository)
+        // 5. Report the resolved count; warn when subtag mode was expected to cover
+        //    something (GR enabled, or explicit includes were configured) but resolved
+        //    to nothing. Only emit the Debug line when there is at least one target,
+        //    to avoid a confusing "0 target(s)" noise line.
+        if (targets.Count == 0 && (discovery.UseGalaxyRepository || discovery.IncludeAttributes.Length > 0))
         {
             _logger.LogWarning(
                 "Alarm subtag watch-list resolved to zero targets; subtag-polling fallback will cover no alarms.");
         }
-        else
+        else if (targets.Count > 0)
         {
             _logger.LogDebug("Resolved alarm subtag watch-list with {TargetCount} target(s).", targets.Count);
         }