small fixes

Author: Peiyingy

gateway-ha/src/main/java/io/trino/gateway/ha/router/BaseRoutingManager.java

@@ -107,7 +107,7 @@ public ProxyBackendConfiguration provideDefaultBackendConfiguration(String user)
      * has no suitable backend unless {@code strictRouting} is true, in which case a 404 is returned.
      */
     @Override
-    public ProxyBackendConfiguration provideBackendConfiguration(String routingGroup, String user, Boolean strictRouting)
+    public ProxyBackendConfiguration provideBackendConfiguration(String routingGroup, String user, boolean strictRouting)
     {
         List<ProxyBackendConfiguration> backends = gatewayBackendManager.getActiveBackends(routingGroup).stream()
                 .filter(backEnd -> isBackendHealthy(backEnd.getName()))

gateway-ha/src/main/java/io/trino/gateway/ha/router/RoutingManager.java

@@ -81,8 +81,8 @@ public interface RoutingManager
      *
      * @param routingGroup the routing group to use for backend selection
      * @param user the user requesting the backend
-     * @param strictRouting whether to enforce isolation
+     * @param strictRouting whether to force strict routing
      * @return the backend configuration for the selected cluster
      */
-    ProxyBackendConfiguration provideBackendConfiguration(String routingGroup, String user, Boolean strictRouting);
+    ProxyBackendConfiguration provideBackendConfiguration(String routingGroup, String user, boolean strictRouting);
 }

gateway-ha/src/main/java/io/trino/gateway/ha/router/schema/RoutingGroupResponse.java

@@ -25,12 +25,13 @@
  Implementations of this interface are used to:
     * Specify the target routing group for a request
     * Provide additional headers that should be added to the request
+    * Specify whether strict routing should be used
  */
 public interface RoutingGroupResponse
 {
     @Nullable String routingGroup();
 
     Map<String, String> externalHeaders();
 
-    Boolean strictRouting();
+    @Nullable Boolean strictRouting();
 }

gateway-ha/src/main/java/io/trino/gateway/ha/router/schema/RoutingSelectorResponse.java

@@ -22,10 +22,10 @@
  * Response from the routing service that includes:
  * - routingGroup: The target routing group for the request (Optional)
  * - externalHeaders: Headers that can be set in the request (Currently can only be set in ExternalRoutingGroupSelector)
- * - strictRouting: If true, the handler must not fall back to default when target group has no available backend;
+ * - strictRouting: If true, the handler must not fall back to default when target group has no available backend (Optional)
  *   instead, a 4xx should be returned.
  */
-public record RoutingSelectorResponse(@Nullable String routingGroup, Map<String, String> externalHeaders, Boolean strictRouting)
+public record RoutingSelectorResponse(@Nullable String routingGroup, Map<String, String> externalHeaders, @Nullable Boolean strictRouting)
         implements RoutingGroupResponse
 {
     public RoutingSelectorResponse {