add config toggle

Author: Robert Pospisil

extensions/smallrye-graphql/deployment/src/main/java/io/quarkus/smallrye/graphql/deployment/SmallRyeGraphQLProcessor.java

@@ -652,6 +652,16 @@ void activateEventing(SmallRyeGraphQLConfig graphQLConfig, BuildProducer<SystemP
         }
     }
 
+    @BuildStep
+    void activateFederationBatchResolving(SmallRyeGraphQLConfig graphQLConfig,
+            BuildProducer<SystemPropertyBuildItem> systemProperties) {
+        if (graphQLConfig.federationBatchResolvingEnabled.isPresent()) {
+            String value = graphQLConfig.federationBatchResolvingEnabled.get().toString();
+            systemProperties.produce(new SystemPropertyBuildItem(ConfigKey.ENABLE_FEDERATION_BATCH_RESOLVING, value));
+            System.setProperty(ConfigKey.ENABLE_FEDERATION_BATCH_RESOLVING, value);
+        }
+    }
+
     /*
      * Decides whether we want to activate GraphQL federation and updates system properties accordingly.
      * If quarkus.smallrye-graphql.federation.enabled is unspecified, enable federation automatically if we see

extensions/smallrye-graphql/runtime/src/main/java/io/quarkus/smallrye/graphql/runtime/SmallRyeGraphQLConfig.java

@@ -27,6 +27,12 @@ public class SmallRyeGraphQLConfig {
     @ConfigItem(name = "federation.enabled")
     public Optional<Boolean> federationEnabled;
 
+    /**
+     * Enable batch resolving for federation. Disabled by default.
+     */
+    @ConfigItem(name = "federation.batch-resolving-enabled")
+    public Optional<Boolean> federationBatchResolvingEnabled;
+
     /**
      * Enable metrics. By default, this is false. If set to true, a metrics extension is required.
      */