Add List-based repository interfaces.

This introduces the interfaces
* `ListCrudRepository`
* `ListQuerydslPredicateExecutor`
* `ListQueryByExampleExecutor`

They return `List` instead of `Iterable` when returning multiple entities.
They can be used in the same way the interfaces without the `List` prefix can be used.

Closes #2535.
Original pull request: #2538.

src/main/java/org/springframework/data/querydsl/ListQuerydslPredicateExecutor.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 org.springframework.data.querydsl;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.function.Function;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.repository.query.FluentQuery;
+
+import com.querydsl.core.types.OrderSpecifier;
+import com.querydsl.core.types.Predicate;
+
+/**
+ * Interface to allow execution of QueryDsl {@link Predicate} instances.This identical to *
+ * {@link QuerydslPredicateExecutor} but returns {@link List} instead of {@link Iterable} where applicable.
+ *
+ * @author Jens Schauder
+ * @since 3.0
+ * @see QuerydslPredicateExecutor
+ */
+public interface ListQuerydslPredicateExecutor<T> {
+
+	/**
+	 * Returns a single entity matching the given {@link Predicate} or {@link Optional#empty()} if none was found.
+	 *
+	 * @param predicate must not be {@literal null}.
+	 * @return a single entity matching the given {@link Predicate} or {@link Optional#empty()} if none was found.
+	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if the predicate yields more than one
+	 *           result.
+	 */
+	Optional<T> findOne(Predicate predicate);
+
+	/**
+	 * Returns all entities matching the given {@link Predicate}. In case no match could be found an empty {@link List} is
+	 * returned.
+	 *
+	 * @param predicate must not be {@literal null}.
+	 * @return all entities matching the given {@link Predicate}.
+	 */
+	List<T> findAll(Predicate predicate);
+
+	/**
+	 * Returns all entities matching the given {@link Predicate} applying the given {@link Sort}. In case no match could
+	 * be found an empty {@link List} is returned.
+	 *
+	 * @param predicate must not be {@literal null}.
+	 * @param sort the {@link Sort} specification to sort the results by, may be {@link Sort#unsorted()}, must not be
+	 *          {@literal null}.
+	 * @return all entities matching the given {@link Predicate}.
+	 */
+	List<T> findAll(Predicate predicate, Sort sort);
+
+	/**
+	 * Returns all entities matching the given {@link Predicate} applying the given {@link OrderSpecifier}s. In case no
+	 * match could be found an empty {@link List} is returned.
+	 *
+	 * @param predicate must not be {@literal null}.
+	 * @param orders the {@link OrderSpecifier}s to sort the results by, must not be {@literal null}.
+	 * @return all entities matching the given {@link Predicate} applying the given {@link OrderSpecifier}s.
+	 */
+	List<T> findAll(Predicate predicate, OrderSpecifier<?>... orders);
+
+	/**
+	 * Returns all entities ordered by the given {@link OrderSpecifier}s.
+	 *
+	 * @param orders the {@link OrderSpecifier}s to sort the results by, must not be {@literal null}.
+	 * @return all entities ordered by the given {@link OrderSpecifier}s.
+	 */
+	List<T> findAll(OrderSpecifier<?>... orders);
+
+	/**
+	 * Returns a {@link Page} of entities matching the given {@link Predicate}. In case no match could be found, an empty
+	 * {@link Page} is returned.
+	 *
+	 * @param predicate must not be {@literal null}.
+	 * @param pageable may be {@link Pageable#unpaged()}, must not be {@literal null}.
+	 * @return a {@link Page} of entities matching the given {@link Predicate}.
+	 */
+	Page<T> findAll(Predicate predicate, Pageable pageable);
+
+	/**
+	 * Returns the number of instances matching the given {@link Predicate}.
+	 *
+	 * @param predicate the {@link Predicate} to count instances for, must not be {@literal null}.
+	 * @return the number of instances matching the {@link Predicate}.
+	 */
+	long count(Predicate predicate);
+
+	/**
+	 * Checks whether the data store contains elements that match the given {@link Predicate}.
+	 *
+	 * @param predicate the {@link Predicate} to use for the existence check, must not be {@literal null}.
+	 * @return {@literal true} if the data store contains elements that match the given {@link Predicate}.
+	 */
+	boolean exists(Predicate predicate);
+
+	/**
+	 * Returns entities matching the given {@link Predicate} applying the {@link Function queryFunction} that defines the
+	 * query and its result type.
+	 *
+	 * @param predicate must not be {@literal null}.
+	 * @param queryFunction the query function defining projection, sorting, and the result type
+	 * @return all entities matching the given {@link Predicate}.
+	 */
+	<S extends T, R> R findBy(Predicate predicate, Function<FluentQuery.FetchableFluentQuery<S>, R> queryFunction);
+}