Assertions for return parameters about archunit HOT 5 CLOSED

import java.util.*;
import com.tngtech.archunit.base.*;
import com.tngtech.archunit.core.domain.*;
import com.tngtech.archunit.core.domain.properties.HasModifiers;
import com.tngtech.archunit.junit.ArchTest;
import com.tngtech.archunit.lang.*;
import static com.tngtech.archunit.core.domain.Formatters.formatLocation;
import static com.tngtech.archunit.core.domain.JavaModifier.PUBLIC;
import static com.tngtech.archunit.core.domain.properties.HasModifiers.Predicates.modifier;
import static com.tngtech.archunit.lang.Priority.MEDIUM;
import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.priority;

public class MethodReturnTypeTest {

    @ArchTest
    public static ArchRule all_public_methods_in_the_controller_layer_should_return_API_response_wrappers = priority(MEDIUM)
            .all(methods().that(areInPackage(PackageMatcher.of("ABC"))))
            .that(arePublic())
            .should(returnType(ApiWrapper.class))
            .because("we don't want to couple the client code directly to the API reponse classes");

    static ClassesTransformer<JavaMethod> methods() {
        return new AbstractClassesTransformer<JavaMethod>("methods") {
            @Override
            public Iterable<JavaMethod> doTransform(JavaClasses javaClasses) {
                List<JavaMethod> methods = new ArrayList<>();
                for (JavaClass javaClass : javaClasses) {
                    methods.addAll(javaClass.getMethods());
                }
                return methods;
            }
        };
    }

    static DescribedPredicate<JavaMember> areInPackage(PackageMatcher packageMatcher) {
        return new DescribedPredicate<JavaMember>("are in " + packageMatcher) {
            @Override
            public boolean apply(JavaMember member) {
                return packageMatcher.matches(member.getOwner().getPackage());
            }
        };
    }

    static DescribedPredicate<HasModifiers> arePublic() {
        return modifier(PUBLIC).as("are public");
    }

    static ArchCondition<JavaMethod> returnType(Class<?> type) {
        return new ArchCondition<JavaMethod>("return type " + type.getName()) {
            @Override
            public void check(JavaMethod method, ConditionEvents events) {
                boolean typeMatches = method.getReturnType().isAssignableTo(type);
                String message = method.getFullName() + " returns " + method.getReturnType().getName() + " " + formatLocation(method.getOwner(), 1);
                events.add(new SimpleConditionEvent(method, typeMatches, message));
            }
        };
    }
}