Properly use ParamConverter to converting the values of collection types

Fixes: quarkusio#27515

extensions/resteasy-reactive/quarkus-resteasy-reactive/deployment/src/test/java/io/quarkus/resteasy/reactive/server/test/providers/ParamConverterTest.java

@@ -0,0 +1,110 @@
+package io.quarkus.resteasy.reactive.server.test.providers;
+
+import static io.restassured.RestAssured.get;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Type;
+import java.util.List;
+import java.util.Set;
+import java.util.UUID;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.ext.ParamConverter;
+import javax.ws.rs.ext.ParamConverterProvider;
+import javax.ws.rs.ext.Provider;
+
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+
+public class ParamConverterTest {
+
+    private static final String STATIC_UUID = "42f425f1-5923-41ca-a43c-713888762c68";
+
+    @RegisterExtension
+    static final QuarkusUnitTest config = new QuarkusUnitTest()
+            .withApplicationRoot((jar) -> jar
+                    .addClasses(UUIDResource.class, UUIDParamConverterProvider.class));
+
+    @Test
+    public void single() {
+        get("/uuid/single?id=whatever")
+                .then()
+                .statusCode(200)
+                .body(Matchers.equalTo(STATIC_UUID));
+    }
+
+    @Test
+    public void set() {
+        get("/uuid/set?id=whatever&id=whatever2")
+                .then()
+                .statusCode(200)
+                .body(Matchers.equalTo(STATIC_UUID));
+    }
+
+    @Test
+    public void list() {
+        get("/uuid/list?id=whatever&id=whatever2")
+                .then()
+                .statusCode(200)
+                .body(Matchers.equalTo(STATIC_UUID + "," + STATIC_UUID));
+    }
+
+    @Path("uuid")
+    public static class UUIDResource {
+
+        @Path("single")
+        @GET
+        public String single(@QueryParam("id") UUID uuid) {
+            return uuid.toString();
+        }
+
+        @Path("set")
+        @GET
+        public String set(@QueryParam("id") Set<UUID> uuids) {
+            return join(uuids.stream());
+        }
+
+        @Path("list")
+        @GET
+        public String list(@QueryParam("id") List<UUID> uuids) {
+            return join(uuids.stream());
+        }
+
+        private static String join(Stream<UUID> uuids) {
+            return uuids.map(UUID::toString).collect(Collectors.joining(","));
+        }
+    }
+
+    @Provider
+    public static class UUIDParamConverterProvider implements ParamConverterProvider {
+        @SuppressWarnings("unchecked")
+        @Override
+        public <T> ParamConverter<T> getConverter(Class<T> rawType, Type genericType, Annotation[] annotations) {
+            if (rawType.equals(UUID.class)) {
+                return (ParamConverter<T>) new UUIDParamConverter();
+            }
+
+            return null;
+        }
+
+        public static class UUIDParamConverter implements ParamConverter<UUID> {
+            @Override
+            public UUID fromString(String value) {
+                return UUID.fromString(STATIC_UUID);
+            }
+
+            @Override
+            public String toString(UUID value) {
+                return value.toString();
+            }
+        }
+
+    }
+}

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/parameters/converters/ListConverter.java

@@ -42,6 +42,11 @@ public void init(ParamConverterProviders deployment, Class<?> rawType, Type gene
             delegate.init(deployment, rawType, genericType, annotations);
     }
 
+    @Override
+    public boolean isForSingleObjectContainer() {
+        return true;
+    }
+
     public ParameterConverter getDelegate() {
         return delegate;
     }

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/parameters/converters/ParameterConverter.java

@@ -11,4 +11,9 @@ public interface ParameterConverter {
     default void init(ParamConverterProviders deployment, Class<?> rawType, Type genericType, Annotation[] annotations) {
 
     }
+
+    // TODO: this API method may be too limiting
+    default boolean isForSingleObjectContainer() {
+        return false;
+    }
 }

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/parameters/converters/SetConverter.java

@@ -43,6 +43,11 @@ public void init(ParamConverterProviders deployment, Class<?> rawType, Type gene
         delegate.init(deployment, rawType, genericType, annotations);
     }
 
+    @Override
+    public boolean isForSingleObjectContainer() {
+        return true;
+    }
+
     public static class SetSupplier implements DelegatingParameterConverterSupplier {
         private ParameterConverterSupplier delegate;
 

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/parameters/converters/SortedSetConverter.java

@@ -47,6 +47,11 @@ public void init(ParamConverterProviders deployment, Class<?> rawType, Type gene
         delegate.init(deployment, rawType, genericType, annotations);
     }
 
+    @Override
+    public boolean isForSingleObjectContainer() {
+        return true;
+    }
+
     public static class SortedSetSupplier implements DelegatingParameterConverterSupplier {
         private ParameterConverterSupplier delegate;
 

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/startup/RuntimeResourceDeployment.java

@@ -6,6 +6,7 @@
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
@@ -345,8 +346,9 @@ public RuntimeResource buildResourceMethod(ResourceClass clazz,
                     Class<?>[] parameterTypes = javaMethod.getParameterTypes();
                     Type[] genericParameterTypes = javaMethod.getGenericParameterTypes();
                     Annotation[][] parameterAnnotations = javaMethod.getParameterAnnotations();
-                    converter.init(paramConverterProviders, parameterTypes[i], genericParameterTypes[i],
-                            parameterAnnotations[i]);
+                    smartInitParameterConverter(i, converter, paramConverterProviders, parameterTypes, genericParameterTypes,
+                            parameterAnnotations);
+
                     // make sure we give the user provided resolvers the chance to convert
                     converter = new RuntimeResolvedConverter(converter);
                     converter.init(paramConverterProviders, parameterTypes[i], genericParameterTypes[i],
@@ -487,6 +489,34 @@ public RuntimeResource buildResourceMethod(ResourceClass clazz,
                 clazz.resourceExceptionMapper());
     }
 
+    /**
+     * This method takes into account the case where a parameter is for example List<UUID>
+     * and we want to allow users to be able to use their implementation of
+     * ParamConverter<UUID>.
+     */
+    private static void smartInitParameterConverter(int i, ParameterConverter quarkusConverter,
+            ParamConverterProviders paramConverterProviders,
+            Class<?>[] parameterTypes, Type[] genericParameterTypes,
+            Annotation[][] parameterAnnotations) {
+        if (quarkusConverter.isForSingleObjectContainer()) {
+
+            if (genericParameterTypes[i] instanceof ParameterizedType) {
+                Type[] genericArguments = ((ParameterizedType) genericParameterTypes[i]).getActualTypeArguments();
+                if (genericArguments.length == 1) {
+                    quarkusConverter.init(paramConverterProviders, loadClass(genericArguments[0].getTypeName()),
+                            genericArguments[0],
+                            parameterAnnotations[i]);
+                    return;
+                }
+            }
+        }
+
+        // TODO: this is almost certainly wrong when genericParameterTypes[i] is a ParameterizedType not handle above,
+        // but there is no obvious way to handle it...
+        quarkusConverter.init(paramConverterProviders, parameterTypes[i], genericParameterTypes[i],
+                parameterAnnotations[i]);
+    }
+
     private static boolean isNotVoid(Class<?> rawEffectiveReturnType) {
         return rawEffectiveReturnType != Void.class
                 && rawEffectiveReturnType != void.class;