Validate required params present before running rules

codegen/src/main/java/software/amazon/awssdk/codegen/poet/rules/EndpointProviderSpec.java

@@ -33,6 +33,7 @@
 import software.amazon.awssdk.codegen.poet.ClassSpec;
 import software.amazon.awssdk.codegen.poet.PoetUtils;
 import software.amazon.awssdk.utils.CompletableFutureUtils;
+import software.amazon.awssdk.utils.Validate;
 
 public class EndpointProviderSpec implements ClassSpec {
     private static final String RULE_SET_FIELD_NAME = "ENDPOINT_RULE_SET";
@@ -132,6 +133,8 @@ private MethodSpec resolveEndpointMethod() {
                                          .addAnnotation(Override.class)
                                          .addParameter(endpointRulesSpecUtils.parametersClassName(), paramsName);
 
+        b.addCode(validateRequiredParams());
+
         b.addStatement("$T res = new $T().evaluate($N, toIdentifierValueMap($N))",
                        endpointRulesSpecUtils.rulesRuntimeClassName("Value"),
                        endpointRulesSpecUtils.rulesRuntimeClassName("DefaultRuleEngine"),
@@ -161,4 +164,21 @@ private MethodSpec ruleSetBuildMethod(TypeSpec.Builder classBuilder) {
         ruleSetCreationSpec.helperMethods().forEach(classBuilder::addMethod);
         return b.build();
     }
+
+    private CodeBlock validateRequiredParams() {
+        CodeBlock.Builder b = CodeBlock.builder();
+
+        Map<String, ParameterModel> parameters = intermediateModel.getEndpointRuleSetModel().getParameters();
+        parameters.entrySet().stream()
+                             .filter(e -> Boolean.TRUE.equals(e.getValue().isRequired()))
+                             .forEach(e -> {
+                                 b.addStatement("$T.notNull($N.$N(), $S)",
+                                                Validate.class,
+                                                "endpointParams",
+                                                endpointRulesSpecUtils.paramMethodName(e.getKey()),
+                                                String.format("Parameter '%s' must not be null", e.getKey()));
+                             });
+
+        return b.build();
+    }
 }

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/rules/endpoint-provider-class.java

@@ -11,6 +11,7 @@
 import software.amazon.awssdk.services.query.endpoints.QueryEndpointProvider;
 import software.amazon.awssdk.utils.CompletableFutureUtils;
 import software.amazon.awssdk.utils.MapUtils;
+import software.amazon.awssdk.utils.Validate;
 
 @Generated("software.amazon.awssdk:codegen")
 @SdkInternalApi
@@ -19,6 +20,7 @@ public final class DefaultQueryEndpointProvider implements QueryEndpointProvider
 
     @Override
     public CompletableFuture<Endpoint> resolveEndpoint(QueryEndpointParams endpointParams) {
+        Validate.notNull(endpointParams.region(), "Parameter 'region' must not be null");
         Value res = new DefaultRuleEngine().evaluate(ENDPOINT_RULE_SET, toIdentifierValueMap(endpointParams));
         try {
             return CompletableFuture.completedFuture(AwsEndpointProviderUtils.valueAsEndpointOrThrow(res));

test/codegen-generated-classes-test/src/test/java/software/amazon/awssdk/services/endpointproviders/EndpointProviderTest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.awssdk.services.endpointproviders;
+
+import static org.assertj.core.api.Assertions.assertThatNoException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.junit.jupiter.api.Test;
+import software.amazon.awssdk.regions.Region;
+import software.amazon.awssdk.services.restjsonendpointproviders.endpoints.RestJsonEndpointProvidersEndpointProvider;
+
+public class EndpointProviderTest {
+    @Test
+    public void resolveEndpoint_requiredParamNotPresent_throws() {
+        assertThatThrownBy(() -> RestJsonEndpointProvidersEndpointProvider.defaultProvider()
+            .resolveEndpoint(r -> {}))
+            .hasMessageContaining("must not be null");
+    }
+
+    @Test
+    public void resolveEndpoint_optionalParamNotPresent_doesNotThrow() {
+        assertThatNoException().isThrownBy(() ->
+                               RestJsonEndpointProvidersEndpointProvider.defaultProvider()
+                                                                        .resolveEndpoint(r -> r.useFips(null)
+                                                                                               .region(Region.of("us-mars-1"))));
+    }
+}