Propagate named interface assignments of types to return and parameter types of methods declared

spring-modulith-api/src/main/java/org/springframework/modulith/NamedInterface.java

@@ -52,4 +52,14 @@
 	 */
 	@AliasFor("value")
 	String[] name() default {};
+
+	/**
+	 * Whether to automatically include types related to the ones declared in the named interface.
+	 * When set to {@code true}, types that appear in public method signatures (parameters and return types)
+	 * of the explicitly declared types will also be considered part of this named interface.
+	 * This is useful to avoid having to explicitly declare all types that are part of the interface's API.
+	 * 
+	 * @return {@code true} to automatically include related types, {@code false} otherwise
+	 */
+	boolean autoIncludeRelatedTypes() default false;
 }

spring-modulith-core/src/main/java/org/springframework/modulith/core/NamedInterfaces.java

@@ -17,13 +17,7 @@
 
 import static java.util.stream.Collectors.*;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Optional;
+import java.util.*;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -303,14 +297,56 @@ private static List<NamedInterface> ofAnnotatedTypes(Classes classes) {
 					}
 
 					NamedInterface.getDefaultedNames(annotation, it.getPackageName())
-							.forEach(name -> mappings.add(name, it));
+							.forEach(name -> {
+								mappings.add(name, it);
+								if(annotation.autoIncludeRelatedTypes()) {
+									mappings.addAll(name, methodSignatureExposedTypes(it));
+								}
+					});
 				});
 
 		return mappings.entrySet().stream() //
 				.map(entry -> NamedInterface.of(entry.getKey(), Classes.of(entry.getValue()))) //
 				.toList();
 	}
 
+    private static List<JavaClass> methodSignatureExposedTypes(JavaClass javaClass) {
+        var dependencies = new HashSet<JavaClass>();
+        var visited = new HashSet<JavaClass>();
+
+        collectExposedTypes(javaClass, dependencies, visited);
+
+        return dependencies.stream()
+                .filter(Types.JavaTypes.IS_NOT_CORE_JAVA_TYPE)
+                .toList();
+    }
+
+    private static void collectExposedTypes(JavaClass type, Set<JavaClass> exposedTypes, Set<JavaClass> visited) {
+        if (visited.contains(type)) {
+            return;
+        }
+
+        visited.add(type);
+
+        type.getAllMethods().forEach(method -> {
+            method.getParameterTypes().forEach(paramType -> {
+                Set<JavaClass> rawTypes = paramType.getAllInvolvedRawTypes();
+                exposedTypes.addAll(rawTypes);
+
+                rawTypes.forEach(rawType -> {
+                    collectExposedTypes(rawType, exposedTypes, visited);
+                });
+            });
+
+            Set<JavaClass> returnRawTypes = method.getReturnType().getAllInvolvedRawTypes();
+            exposedTypes.addAll(returnRawTypes);
+
+            returnRawTypes.forEach(rawType -> {
+                collectExposedTypes(rawType, exposedTypes, visited);
+            });
+        });
+    }
+
 	/**
 	 * A builder API to manually construct {@link NamedInterfaces} instances. Allows selecting packages to create
 	 * {@link NamedInterface} instances for based on excluding and including predicates, name matches etc. Will always

spring-modulith-core/src/test/java/autoinclude/APublicService.java

@@ -0,0 +1,8 @@
+package autoinclude;
+
+import autoinclude.dtos.MyDTO;
+
+public interface APublicService {
+
+    void doSomething(MyDTO dto);
+}

spring-modulith-core/src/test/java/autoinclude/AutoincludeService.java

@@ -0,0 +1,9 @@
+package autoinclude;
+
+import autoinclude.dtos.MyDTO;
+
+@org.springframework.modulith.NamedInterface(name = "AutoincludeService", autoIncludeRelatedTypes = true)
+public interface AutoincludeService {
+
+    void doSomething(MyDTO dto);
+}

spring-modulith-core/src/test/java/autoinclude/NoAutoincludeService.java

@@ -0,0 +1,9 @@
+package autoinclude;
+
+import autoinclude.dtos.MyDTO;
+
+@org.springframework.modulith.NamedInterface(name = "NoAutoincludeService", autoIncludeRelatedTypes = false)
+public interface NoAutoincludeService {
+
+    void doSomething(MyDTO dto);
+}

spring-modulith-core/src/test/java/autoinclude/dtos/MyDTO.java

@@ -0,0 +1,4 @@
+package autoinclude.dtos;
+
+public record MyDTO(String name, MyRelatedDTO related) {
+}

spring-modulith-core/src/test/java/autoinclude/dtos/MyEnum.java

@@ -0,0 +1,5 @@
+package autoinclude.dtos;
+
+public enum MyEnum {
+    ONE, TWO, THREE
+}

spring-modulith-core/src/test/java/autoinclude/dtos/MyRelatedDTO.java

@@ -0,0 +1,4 @@
+package autoinclude.dtos;
+
+public record MyRelatedDTO(String name) {
+}

spring-modulith-core/src/test/java/autoinclude/events/AnAutoincludeEvent.java

@@ -0,0 +1,7 @@
+package autoinclude.events;
+
+import org.springframework.modulith.NamedInterface;
+
+@NamedInterface(name = "events.AnAutoincludeEvent", autoIncludeRelatedTypes = true)
+public record AnAutoincludeEvent(RelatedType relatedType, AnEnum anEnum) {
+}

spring-modulith-core/src/test/java/autoinclude/events/AnEnum.java

@@ -0,0 +1,5 @@
+package autoinclude.events;
+
+public enum AnEnum {
+    ONE, TWO, THREE
+}

spring-modulith-core/src/test/java/autoinclude/events/NotAutoincludeEvent.java

@@ -0,0 +1,7 @@
+package autoinclude.events;
+
+import org.springframework.modulith.NamedInterface;
+
+@NamedInterface(name = "events.NotAutoincludeEvent", autoIncludeRelatedTypes = false)
+public record NotAutoincludeEvent(RelatedType relatedType, AnEnum anEnum) {
+}

spring-modulith-core/src/test/java/autoinclude/events/RelatedType.java

@@ -0,0 +1,4 @@
+package autoinclude.events;
+
+public record RelatedType(String name) {
+}

spring-modulith-core/src/test/java/autoinclude/package-info.java

@@ -0,0 +1,2 @@
+@org.springframework.modulith.ApplicationModule
+package autoinclude;