diff --git a/modules/data-streams/src/main/java/org/elasticsearch/datastreams/rest/RestGetDataStreamsAction.java b/modules/data-streams/src/main/java/org/elasticsearch/datastreams/rest/RestGetDataStreamsAction.java
index 23472b4830fa3..da55376fb403b 100644
--- a/modules/data-streams/src/main/java/org/elasticsearch/datastreams/rest/RestGetDataStreamsAction.java
+++ b/modules/data-streams/src/main/java/org/elasticsearch/datastreams/rest/RestGetDataStreamsAction.java
@@ -29,6 +29,23 @@
 @ServerlessScope(Scope.PUBLIC)
 public class RestGetDataStreamsAction extends BaseRestHandler {
 
+    private static final Set<String> SUPPORTED_QUERY_PARAMETERS = Set.copyOf(
+        Sets.union(
+            RestRequest.INTERNAL_MARKER_REQUEST_PARAMETERS,
+            Set.of(
+                "name",
+                "include_defaults",
+                "timeout",
+                "master_timeout",
+                IndicesOptions.WildcardOptions.EXPAND_WILDCARDS,
+                IndicesOptions.ConcreteTargetOptions.IGNORE_UNAVAILABLE,
+                IndicesOptions.WildcardOptions.ALLOW_NO_INDICES,
+                IndicesOptions.GatekeeperOptions.IGNORE_THROTTLED,
+                "verbose"
+            )
+        )
+    );
+
     @Override
     public String getName() {
         return "get_data_streams_action";
@@ -63,19 +80,6 @@ public Set<String> supportedCapabilities() {
 
     @Override
     public Set<String> supportedQueryParameters() {
-        return Sets.union(
-            RestRequest.INTERNAL_MARKER_REQUEST_PARAMETERS,
-            Set.of(
-                "name",
-                "include_defaults",
-                "timeout",
-                "master_timeout",
-                IndicesOptions.WildcardOptions.EXPAND_WILDCARDS,
-                IndicesOptions.ConcreteTargetOptions.IGNORE_UNAVAILABLE,
-                IndicesOptions.WildcardOptions.ALLOW_NO_INDICES,
-                IndicesOptions.GatekeeperOptions.IGNORE_THROTTLED,
-                "verbose"
-            )
-        );
+        return SUPPORTED_QUERY_PARAMETERS;
     }
 }
diff --git a/server/src/main/java/org/elasticsearch/rest/BaseRestHandler.java b/server/src/main/java/org/elasticsearch/rest/BaseRestHandler.java
index 5f12a2bdd6783..99fa3e0166963 100644
--- a/server/src/main/java/org/elasticsearch/rest/BaseRestHandler.java
+++ b/server/src/main/java/org/elasticsearch/rest/BaseRestHandler.java
@@ -85,6 +85,7 @@ public final long getUsageCount() {
     public final void handleRequest(RestRequest request, RestChannel channel, NodeClient client) throws Exception {
         // check if the query has any parameters that are not in the supported set (if declared)
         Set<String> supported = allSupportedParameters();
+        assert supported == allSupportedParameters() : getName() + ": did not return same instance from allSupportedParameters()";
         if (supported != null) {
             var allSupported = Sets.union(
                 RestResponse.RESPONSE_PARAMS,
diff --git a/server/src/main/java/org/elasticsearch/rest/RestController.java b/server/src/main/java/org/elasticsearch/rest/RestController.java
index 7fcc75ad65872..924cd361c671d 100644
--- a/server/src/main/java/org/elasticsearch/rest/RestController.java
+++ b/server/src/main/java/org/elasticsearch/rest/RestController.java
@@ -397,6 +397,8 @@ public boolean checkSupported(
 
             if (handler != null) {
                 var supportedParams = handler.supportedQueryParameters();
+                assert supportedParams == handler.supportedQueryParameters()
+                    : handler.getName() + ": did not return same instance from supportedQueryParameters()";
                 return (supportedParams == null || supportedParams.containsAll(parameters))
                     && handler.supportedCapabilities().containsAll(capabilities);
             }
diff --git a/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestClusterStatsAction.java b/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestClusterStatsAction.java
index 449f5d5b770c4..d46472ff8d6c2 100644
--- a/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestClusterStatsAction.java
+++ b/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestClusterStatsAction.java
@@ -32,8 +32,11 @@
 public class RestClusterStatsAction extends BaseRestHandler {
 
     private static final Set<String> SUPPORTED_CAPABILITIES = Set.of("human-readable-total-docs-size");
-    private static final Set<String> SUPPORTED_CAPABILITIES_CCS_STATS = Sets.union(SUPPORTED_CAPABILITIES, Set.of("ccs-stats"));
+    private static final Set<String> SUPPORTED_CAPABILITIES_CCS_STATS = Sets.copyOf(
+        Sets.union(SUPPORTED_CAPABILITIES, Set.of("ccs-stats"))
+    );
     public static final FeatureFlag CCS_TELEMETRY_FEATURE_FLAG = new FeatureFlag("ccs_telemetry");
+    private static final Set<String> SUPPORTED_QUERY_PARAMETERS = Set.of("include_remotes", "nodeId", REST_TIMEOUT_PARAM);
 
     @Override
     public List<Route> routes() {
@@ -47,7 +50,7 @@ public String getName() {
 
     @Override
     public Set<String> supportedQueryParameters() {
-        return Set.of("include_remotes", "nodeId", REST_TIMEOUT_PARAM);
+        return SUPPORTED_QUERY_PARAMETERS;
     }
 
     @Override
diff --git a/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestNodesCapabilitiesAction.java b/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestNodesCapabilitiesAction.java
index ad405656631b0..bc7f8c7e12449 100644
--- a/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestNodesCapabilitiesAction.java
+++ b/server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestNodesCapabilitiesAction.java
@@ -32,6 +32,14 @@ public class RestNodesCapabilitiesAction extends BaseRestHandler {
 
     public static final NodeFeature CAPABILITIES_ACTION = new NodeFeature("rest.capabilities_action");
     public static final NodeFeature LOCAL_ONLY_CAPABILITIES = new NodeFeature("rest.local_only_capabilities");
+    private static final Set<String> SUPPORTED_QUERY_PARAMETERS = Set.of(
+        "timeout",
+        "method",
+        "path",
+        "parameters",
+        "capabilities",
+        "local_only"
+    );
 
     @Override
     public List<Route> routes() {
@@ -40,7 +48,7 @@ public List<Route> routes() {
 
     @Override
     public Set<String> supportedQueryParameters() {
-        return Set.of("timeout", "method", "path", "parameters", "capabilities", "local_only");
+        return SUPPORTED_QUERY_PARAMETERS;
     }
 
     @Override