Improve custom project request arrangement

This commit improves the use case of configuring a custom ProjectRequest
by enforcing consistently a particular type using a generic.

As a result, `ProjectGenerationInvoker` is no longer exposed as a bean
as it is the responsibility of the custom `ProjectGenerationController`
to provide one that matches the requested `ProjectRequest` type.

See gh-990

initializr-web/src/main/java/io/spring/initializr/web/autoconfigure/InitializrAutoConfiguration.java

@@ -40,7 +40,7 @@ import io.spring.initializr.web.controller.ProjectMetadataController;
 import io.spring.initializr.web.controller.SpringCliDistributionController;
 import io.spring.initializr.web.project.DefaultProjectRequestToDescriptionConverter;
 import io.spring.initializr.web.project.ProjectGenerationInvoker;
-import io.spring.initializr.web.project.ProjectRequestToDescriptionConverter;
+import io.spring.initializr.web.project.ProjectRequest;
 import io.spring.initializr.web.support.DefaultDependencyMetadataProvider;
 import io.spring.initializr.web.support.DefaultInitializrMetadataProvider;
 import io.spring.initializr.web.support.DefaultInitializrMetadataUpdateStrategy;
@@ -61,7 +61,6 @@ import org.springframework.cache.Cache;
 import org.springframework.cache.CacheManager;
 import org.springframework.cache.support.NoOpCache;
 import org.springframework.context.ApplicationContext;
-import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
@@ -145,7 +144,9 @@ public class InitializrAutoConfiguration {
 		@Bean
 		@ConditionalOnMissingBean
 		ProjectGenerationController projectGenerationController(InitializrMetadataProvider metadataProvider,
-				ProjectGenerationInvoker projectGenerationInvoker) {
+				ApplicationContext applicationContext) {
+			ProjectGenerationInvoker<ProjectRequest> projectGenerationInvoker = new ProjectGenerationInvoker<>(
+					applicationContext, new DefaultProjectRequestToDescriptionConverter());
 			return new DefaultProjectGenerationController(metadataProvider, projectGenerationInvoker);
 		}
 
@@ -169,15 +170,6 @@ public class InitializrAutoConfiguration {
 			return new SpringCliDistributionController(metadataProvider);
 		}
 
-		@Bean
-		@ConditionalOnMissingBean
-		ProjectGenerationInvoker projectGenerationInvoker(ApplicationContext applicationContext,
-				ApplicationEventPublisher eventPublisher,
-				ObjectProvider<ProjectRequestToDescriptionConverter> projectRequestToDescriptionConverter) {
-			return new ProjectGenerationInvoker(applicationContext, eventPublisher, projectRequestToDescriptionConverter
-					.getIfAvailable(DefaultProjectRequestToDescriptionConverter::new));
-		}
-
 		@Bean
 		InitializrModule InitializrJacksonModule() {
 			return new InitializrModule();

initializr-web/src/main/java/io/spring/initializr/web/controller/DefaultProjectGenerationController.java

@@ -32,7 +32,7 @@ import io.spring.initializr.web.project.WebProjectRequest;
 public class DefaultProjectGenerationController extends ProjectGenerationController<ProjectRequest> {
 
 	public DefaultProjectGenerationController(InitializrMetadataProvider metadataProvider,
-			ProjectGenerationInvoker projectGenerationInvoker) {
+			ProjectGenerationInvoker<ProjectRequest> projectGenerationInvoker) {
 		super(metadataProvider, projectGenerationInvoker);
 	}
 

initializr-web/src/main/java/io/spring/initializr/web/controller/ProjectGenerationController.java

@@ -73,10 +73,10 @@ public abstract class ProjectGenerationController<R extends ProjectRequest> {
 
 	private final InitializrMetadataProvider metadataProvider;
 
-	private final ProjectGenerationInvoker projectGenerationInvoker;
+	private final ProjectGenerationInvoker<R> projectGenerationInvoker;
 
 	public ProjectGenerationController(InitializrMetadataProvider metadataProvider,
-			ProjectGenerationInvoker projectGenerationInvoker) {
+			ProjectGenerationInvoker<R> projectGenerationInvoker) {
 		this.metadataProvider = metadataProvider;
 		this.projectGenerationInvoker = projectGenerationInvoker;
 	}

initializr-web/src/main/java/io/spring/initializr/web/project/DefaultProjectRequestToDescriptionConverter.java

@@ -42,7 +42,8 @@ import org.springframework.util.StringUtils;
  * @author Madhura Bhave
  * @author HaiTao Zhang
  */
-public class DefaultProjectRequestToDescriptionConverter implements ProjectRequestToDescriptionConverter {
+public class DefaultProjectRequestToDescriptionConverter
+		implements ProjectRequestToDescriptionConverter<ProjectRequest> {
 
 	private static final Version VERSION_1_5_0 = Version.parse("1.5.0.RELEASE");
 

initializr-web/src/main/java/io/spring/initializr/web/project/ProjectGenerationInvoker.java

@@ -45,20 +45,26 @@ import org.springframework.util.FileSystemUtils;
  * Invokes the project generation API. This is an intermediate layer that can consume a
  * {@link ProjectRequest} and trigger project generation based on the request.
  *
+ * @param <R> the concrete {@link ProjectRequest} type
  * @author Madhura Bhave
  */
-public class ProjectGenerationInvoker {
+public class ProjectGenerationInvoker<R extends ProjectRequest> {
 
 	private final ApplicationContext parentApplicationContext;
 
 	private final ApplicationEventPublisher eventPublisher;
 
-	private final ProjectRequestToDescriptionConverter requestConverter;
+	private final ProjectRequestToDescriptionConverter<R> requestConverter;
 
 	private transient Map<Path, List<Path>> temporaryFiles = new LinkedHashMap<>();
 
 	public ProjectGenerationInvoker(ApplicationContext parentApplicationContext,
-			ApplicationEventPublisher eventPublisher, ProjectRequestToDescriptionConverter requestConverter) {
+			ProjectRequestToDescriptionConverter<R> requestConverter) {
+		this(parentApplicationContext, parentApplicationContext, requestConverter);
+	}
+
+	protected ProjectGenerationInvoker(ApplicationContext parentApplicationContext,
+			ApplicationEventPublisher eventPublisher, ProjectRequestToDescriptionConverter<R> requestConverter) {
 		this.parentApplicationContext = parentApplicationContext;
 		this.eventPublisher = eventPublisher;
 		this.requestConverter = requestConverter;
@@ -70,7 +76,7 @@ public class ProjectGenerationInvoker {
 	 * @param request the project request
 	 * @return the {@link ProjectGenerationResult}
 	 */
-	public ProjectGenerationResult invokeProjectStructureGeneration(ProjectRequest request) {
+	public ProjectGenerationResult invokeProjectStructureGeneration(R request) {
 		InitializrMetadata metadata = this.parentApplicationContext.getBean(InitializrMetadataProvider.class).get();
 		try {
 			ProjectDescription description = this.requestConverter.convert(request, metadata);
@@ -86,7 +92,7 @@ public class ProjectGenerationInvoker {
 		}
 	}
 
-	private ProjectAssetGenerator<ProjectGenerationResult> generateProject(ProjectRequest request) {
+	private ProjectAssetGenerator<ProjectGenerationResult> generateProject(R request) {
 		return (context) -> {
 			Path projectDir = new DefaultProjectAssetGenerator().generate(context);
 			publishProjectGeneratedEvent(request, context);
@@ -101,7 +107,7 @@ public class ProjectGenerationInvoker {
 	 * @param request the project request
 	 * @return the generated build content
 	 */
-	public byte[] invokeBuildGeneration(ProjectRequest request) {
+	public byte[] invokeBuildGeneration(R request) {
 		InitializrMetadata metadata = this.parentApplicationContext.getBean(InitializrMetadataProvider.class).get();
 		try {
 			ProjectDescription description = this.requestConverter.convert(request, metadata);
@@ -115,7 +121,7 @@ public class ProjectGenerationInvoker {
 		}
 	}
 
-	private ProjectAssetGenerator<byte[]> generateBuild(ProjectRequest request) {
+	private ProjectAssetGenerator<byte[]> generateBuild(R request) {
 		return (context) -> {
 			byte[] content = generateBuild(context);
 			publishProjectGeneratedEvent(request, context);
@@ -180,13 +186,13 @@ public class ProjectGenerationInvoker {
 				context.getBean(ProjectDescription.class).getPlatformVersion()));
 	}
 
-	private void publishProjectGeneratedEvent(ProjectRequest request, ProjectGenerationContext context) {
+	private void publishProjectGeneratedEvent(R request, ProjectGenerationContext context) {
 		InitializrMetadata metadata = context.getBean(InitializrMetadata.class);
 		ProjectGeneratedEvent event = new ProjectGeneratedEvent(request, metadata);
 		this.eventPublisher.publishEvent(event);
 	}
 
-	private void publishProjectFailedEvent(ProjectRequest request, InitializrMetadata metadata, Exception cause) {
+	private void publishProjectFailedEvent(R request, InitializrMetadata metadata, Exception cause) {
 		ProjectFailedEvent event = new ProjectFailedEvent(request, metadata, cause);
 		this.eventPublisher.publishEvent(event);
 	}

initializr-web/src/main/java/io/spring/initializr/web/project/ProjectRequestToDescriptionConverter.java

@@ -22,10 +22,11 @@ import io.spring.initializr.metadata.InitializrMetadata;
 /**
  * Convert a {@link ProjectRequest} to a {@link ProjectDescription}.
  *
+ * @param <R> the concrete {@link ProjectRequest} type
  * @author Stephane Nicoll
  */
 @FunctionalInterface
-public interface ProjectRequestToDescriptionConverter {
+public interface ProjectRequestToDescriptionConverter<R extends ProjectRequest> {
 
 	/**
 	 * Validate and convert the specified {@link ProjectRequest} to a
@@ -35,6 +36,6 @@ public interface ProjectRequestToDescriptionConverter {
 	 * @return a validated {@link ProjectDescription} to use to generate a project that
 	 * matches the specified {@code request}
 	 */
-	ProjectDescription convert(ProjectRequest request, InitializrMetadata metadata);
+	ProjectDescription convert(R request, InitializrMetadata metadata);
 
 }

initializr-web/src/test/java/io/spring/initializr/web/autoconfigure/InitializrAutoConfigurationTests.java

@@ -23,8 +23,6 @@ import io.spring.initializr.web.controller.CommandLineMetadataController;
 import io.spring.initializr.web.controller.ProjectGenerationController;
 import io.spring.initializr.web.controller.ProjectMetadataController;
 import io.spring.initializr.web.controller.SpringCliDistributionController;
-import io.spring.initializr.web.project.ProjectGenerationInvoker;
-import io.spring.initializr.web.project.ProjectRequestToDescriptionConverter;
 import io.spring.initializr.web.support.DefaultInitializrMetadataUpdateStrategy;
 import io.spring.initializr.web.support.InitializrMetadataUpdateStrategy;
 import org.junit.jupiter.api.Test;
@@ -129,7 +127,6 @@ class InitializrAutoConfigurationTests {
 				.withConfiguration(BASIC_AUTO_CONFIGURATIONS);
 		webContextRunner.run((context) -> {
 			assertThat(context).hasSingleBean(InitializrWebConfig.class);
-			assertThat(context).hasSingleBean(ProjectGenerationInvoker.class);
 			assertThat(context).hasSingleBean(ProjectGenerationController.class);
 			assertThat(context).hasSingleBean(ProjectMetadataController.class);
 			assertThat(context).hasSingleBean(CommandLineMetadataController.class);
@@ -138,12 +135,12 @@ class InitializrAutoConfigurationTests {
 	}
 
 	@Test
-	void autoConfigWithCustomProjectRequestConverter() {
+	void autoConfigWithCustomProjectGenerationController() {
 		new WebApplicationContextRunner().withConfiguration(BASIC_AUTO_CONFIGURATIONS)
-				.withUserConfiguration(CustomProjectRequestToDescriptionConverter.class).run((context) -> {
-					assertThat(context).hasSingleBean(ProjectGenerationInvoker.class);
-					assertThat(context.getBean(ProjectGenerationInvoker.class)).hasFieldOrPropertyWithValue(
-							"requestConverter", context.getBean("testProjectRequestToDescriptionConverter"));
+				.withUserConfiguration(CustomProjectGenerationController.class).run((context) -> {
+					assertThat(context).hasSingleBean(ProjectGenerationController.class);
+					assertThat(context.getBean(ProjectGenerationController.class))
+							.isSameAs(context.getBean("testProjectGenerationController"));
 				});
 
 	}
@@ -223,11 +220,11 @@ class InitializrAutoConfigurationTests {
 	}
 
 	@Configuration
-	static class CustomProjectRequestToDescriptionConverter {
+	static class CustomProjectGenerationController {
 
 		@Bean
-		ProjectRequestToDescriptionConverter testProjectRequestToDescriptionConverter() {
-			return mock(ProjectRequestToDescriptionConverter.class);
+		ProjectGenerationController<?> testProjectGenerationController() {
+			return mock(ProjectGenerationController.class);
 		}
 
 	}

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/CustomProjectGenerationController.java

@@ -31,7 +31,7 @@ import io.spring.initializr.web.project.ProjectGenerationInvoker;
 class CustomProjectGenerationController extends ProjectGenerationController<CustomProjectRequest> {
 
 	CustomProjectGenerationController(InitializrMetadataProvider metadataProvider,
-			ProjectGenerationInvoker projectGenerationInvoker) {
+			ProjectGenerationInvoker<CustomProjectRequest> projectGenerationInvoker) {
 		super(metadataProvider, projectGenerationInvoker);
 	}
 

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/ProjectGenerationControllerCustomRequestIntegrationTests.java

@@ -25,10 +25,10 @@ import io.spring.initializr.web.controller.ProjectGenerationController;
 import io.spring.initializr.web.controller.custom.ProjectGenerationControllerCustomRequestIntegrationTests.CustomProjectGenerationConfiguration;
 import io.spring.initializr.web.project.DefaultProjectRequestToDescriptionConverter;
 import io.spring.initializr.web.project.ProjectGenerationInvoker;
-import io.spring.initializr.web.project.ProjectRequest;
 import io.spring.initializr.web.project.ProjectRequestToDescriptionConverter;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -73,25 +73,22 @@ public class ProjectGenerationControllerCustomRequestIntegrationTests
 
 		@Bean
 		CustomProjectGenerationController customProjectGenerationController(InitializrMetadataProvider metadataProvider,
-				ProjectGenerationInvoker projectGenerationInvoker) {
+				ApplicationContext applicationContext) {
+			ProjectGenerationInvoker<CustomProjectRequest> projectGenerationInvoker = new ProjectGenerationInvoker<>(
+					applicationContext, new CustomProjectRequestToDescriptionConverter());
 			return new CustomProjectGenerationController(metadataProvider, projectGenerationInvoker);
 		}
 
-		@Bean
-		ProjectRequestToDescriptionConverter customProjectRequestToDescriptionConverter() {
-			return new CustomProjectRequestToDescriptionConverter();
-		}
-
 	}
 
-	static class CustomProjectRequestToDescriptionConverter implements ProjectRequestToDescriptionConverter {
+	static class CustomProjectRequestToDescriptionConverter
+			implements ProjectRequestToDescriptionConverter<CustomProjectRequest> {
 
 		@Override
-		public ProjectDescription convert(ProjectRequest request, InitializrMetadata metadata) {
-			CustomProjectRequest customRequest = (CustomProjectRequest) request;
+		public ProjectDescription convert(CustomProjectRequest request, InitializrMetadata metadata) {
 			CustomProjectDescription description = new CustomProjectDescription();
 			new DefaultProjectRequestToDescriptionConverter().convert(request, description, metadata);
-			description.setCustomFlag(customRequest.isCustomFlag());
+			description.setCustomFlag(request.isCustomFlag());
 			// Override attributes for test purposes
 			description.setPackageName("org.example.custom");
 			description.setApplicationName("CustomApp");