Fix mispelling of ClassUtils.getNumberOfOccurrences(..).

* Re-implement getNumberOfOccurrences(..) in terms of a Stream.
* Deprecate the mispelled getNumberOfOccurences(..) method and delegate to the new getNumberOfOccurrences(..) method.
* Edit Javadoc.

Closes #2600.

src/main/java/org/springframework/data/repository/query/QueryMethod.java

@@ -70,7 +70,7 @@ public class QueryMethod {
 		Assert.notNull(factory, "ProjectionFactory must not be null!");
 
 		Parameters.TYPES.stream()
-				.filter(type -> getNumberOfOccurences(method, type) > 1)
+				.filter(type -> getNumberOfOccurrences(method, type) > 1)
 				.findFirst().ifPresent(type -> {
 					throw new IllegalStateException(
 							String.format("Method must have only one argument of type %s! Offending method: %s",

src/main/java/org/springframework/data/repository/util/ClassUtils.java

@@ -24,6 +24,7 @@ import java.util.function.Consumer;
 import org.springframework.data.repository.Repository;
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.TypeInformation;
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
@@ -104,22 +105,28 @@ public abstract class ClassUtils {
 	}
 
 	/**
-	 * Returns the number of occurences of the given type in the given {@link Method}s parameters.
-	 *
-	 * @param method
-	 * @param type
-	 * @return
+	 * @deprecated Use {@link #getNumberOfOccurrences(Method, Class)}.
 	 */
-	public static int getNumberOfOccurences(Method method, Class<?> type) {
+	@Deprecated
+	public static int getNumberOfOccurences(@NonNull Method method, @NonNull Class<?> type) {
+		return getNumberOfOccurrences(method, type);
+	}
 
-		int result = 0;
-		for (Class<?> clazz : method.getParameterTypes()) {
-			if (type.equals(clazz)) {
-				result++;
-			}
-		}
+	/**
+	 * Returns the number of occurrences for the given {@link Method#getParameterTypes() parameter type}
+	 * in the given {@link Method}.
+	 *
+	 * @param method {@link Method} to evaluate.
+	 * @param parameterType {@link Class} of the {@link Method} parameter type to count.
+	 * @return the number of occurrences for the given {@link Method#getParameterTypes() parameter type}
+	 * in the given {@link Method}.
+	 * @see java.lang.reflect.Method#getParameterTypes()
+	 */
+	public static int getNumberOfOccurrences(@NonNull Method method, @NonNull Class<?> parameterType) {
 
-		return result;
+		return (int) Arrays.stream(method.getParameterTypes())
+				.filter(parameterType::equals)
+				.count();
 	}
 
 	/**

src/test/java/org/springframework/data/repository/util/ClassUtilsUnitTests.java

@@ -15,10 +15,11 @@
  */
 package org.springframework.data.repository.util;
 
-import static org.assertj.core.api.Assertions.*;
-import static org.springframework.data.repository.util.ClassUtils.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 import java.io.Serializable;
+import java.lang.reflect.Method;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.Future;
@@ -26,33 +27,62 @@ import java.util.concurrent.Future;
 import org.junit.jupiter.api.Test;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Sort;
 import org.springframework.data.repository.Repository;
 import org.springframework.scheduling.annotation.Async;
 
 /**
- * Unit test for {@link ClassUtils}.
+ * Unit tests for {@link ClassUtils}.
  *
  * @author Oliver Gierke
+ * @author John Blum
  */
 class ClassUtilsUnitTests {
 
 	@Test
 	void rejectsInvalidReturnType() {
-		assertThatIllegalStateException().isThrownBy(() -> assertReturnTypeAssignable(
+		assertThatIllegalStateException().isThrownBy(() -> ClassUtils.assertReturnTypeAssignable(
 				SomeDao.class.getMethod("findByFirstname", Pageable.class, String.class), User.class));
 	}
 
 	@Test
 	void determinesValidFieldsCorrectly() {
 
-		assertThat(hasProperty(User.class, "firstname")).isTrue();
-		assertThat(hasProperty(User.class, "Firstname")).isTrue();
-		assertThat(hasProperty(User.class, "address")).isFalse();
+		assertThat(ClassUtils.hasProperty(User.class, "firstname")).isTrue();
+		assertThat(ClassUtils.hasProperty(User.class, "Firstname")).isTrue();
+		assertThat(ClassUtils.hasProperty(User.class, "address")).isFalse();
 	}
 
 	@Test // DATACMNS-769
 	void unwrapsWrapperTypesBeforeAssignmentCheck() throws Exception {
-		assertReturnTypeAssignable(UserRepository.class.getMethod("findAsync", Pageable.class), Page.class);
+		ClassUtils.assertReturnTypeAssignable(UserRepository.class.getMethod("findAsync", Pageable.class),
+				Page.class);
+	}
+
+	@Test
+	public void numberOfOccurrencesForMultipleMethodParametersOfType() throws Exception {
+
+		Method findByAddress = AnotherDao.class.getMethod("findByAddress", Pageable.class, Pageable.class);
+
+		assertThat(ClassUtils.getNumberOfOccurrences(findByAddress, Pageable.class)).isEqualTo(2);
+	}
+
+	@Test
+	public void numberOfOccurrencesForNoMethodParameterOfType() throws Exception {
+
+		Method findByAddress = AnotherDao.class.getMethod("findByAddress", Pageable.class, Pageable.class);
+
+		assertThat(ClassUtils.getNumberOfOccurrences(findByAddress, Sort.class)).isZero();
+		assertThat(ClassUtils.getNumberOfOccurrences(findByAddress, Page.class)).isZero();
+	}
+
+	@Test
+	public void numberOfOccurrencesForSingleMethodParameterOfType() throws Exception {
+
+		Method findByFirstname = SomeDao.class.getMethod("findByFirstname", Pageable.class, String.class);
+
+		assertThat(ClassUtils.getNumberOfOccurrences(findByFirstname, Pageable.class)).isOne();
+		assertThat(ClassUtils.getNumberOfOccurrences(findByFirstname, String.class)).isOne();
 	}
 
 	@SuppressWarnings("unused")
@@ -66,7 +96,7 @@ class ClassUtilsUnitTests {
 		}
 	}
 
-	static interface UserRepository extends Repository<User, Integer> {
+	interface UserRepository extends Repository<User, Integer> {
 
 		@Async
 		Future<Page<User>> findAsync(Pageable pageable);
@@ -81,6 +111,12 @@ class ClassUtilsUnitTests {
 		List<Map<String, Object>> anotherMethod();
 	}
 
+	interface AnotherDao extends Repository<User, Integer> {
+
+		Page<User> findByAddress(Pageable pageableOne, Pageable pageableTwo);
+
+	}
+
 	class GenericType<T> {
 
 	}