Introduce ObjectUtils#nullSafeHash(Object... element)

This commit deprecates the various nullSafeHashCode methods taking array
types as they are superseded by Arrays.hashCode now. This means that
the now only remaining nullSafeHashCode method does not trigger a
warning only if the target type is not an array. At the same time, there
are multiple use of this method on several elements, handling the
accumulation of hash codes.

For that reason, this commit also introduces a nullSafeHash that takes
an array of elements. The only difference between Objects.hash is that
this method handles arrays.

The codebase has been reviewed to use any of those two methods when it
is possible.

Closes gh-29051

spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJExpressionPointcut.java

@@ -525,11 +525,8 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = ObjectUtils.nullSafeHashCode(getExpression());
-		hashCode = 31 * hashCode + ObjectUtils.nullSafeHashCode(this.pointcutDeclarationScope);
-		hashCode = 31 * hashCode + ObjectUtils.nullSafeHashCode(this.pointcutParameterNames);
-		hashCode = 31 * hashCode + ObjectUtils.nullSafeHashCode(this.pointcutParameterTypes);
-		return hashCode;
+		return ObjectUtils.nullSafeHash(getExpression(), this.pointcutDeclarationScope,
+				this.pointcutParameterNames, this.pointcutParameterTypes);
 	}
 
 	@Override

spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java

@@ -16,6 +16,8 @@
 
 package org.springframework.aop.aspectj;
 
+import java.util.Objects;
+
 import org.aspectj.weaver.tools.PointcutParser;
 import org.aspectj.weaver.tools.TypePatternMatcher;
 
@@ -124,7 +126,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.typePattern);
+		return Objects.hashCode(this.typePattern);
 	}
 
 	@Override

spring-aop/src/main/java/org/springframework/aop/support/ClassFilters.java

@@ -129,7 +129,7 @@ public boolean equals(@Nullable Object other) {
 
 		@Override
 		public int hashCode() {
-			return ObjectUtils.nullSafeHashCode(this.filters);
+			return Arrays.hashCode(this.filters);
 		}
 
 		@Override
@@ -170,7 +170,7 @@ public boolean equals(@Nullable Object other) {
 
 		@Override
 		public int hashCode() {
-			return ObjectUtils.nullSafeHashCode(this.filters);
+			return Arrays.hashCode(this.filters);
 		}
 
 		@Override

spring-aop/src/main/java/org/springframework/aop/target/AbstractBeanFactoryBasedTargetSource.java

@@ -17,6 +17,7 @@
 package org.springframework.aop.target;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -190,7 +191,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return getClass().hashCode() * 13 + ObjectUtils.nullSafeHashCode(this.targetBeanName);
+		return Objects.hash(getClass(), this.targetBeanName);
 	}
 
 	@Override

spring-aop/src/main/java/org/springframework/aop/target/EmptyTargetSource.java

@@ -17,6 +17,7 @@
 package org.springframework.aop.target;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 import org.springframework.aop.TargetSource;
 import org.springframework.lang.Nullable;
@@ -140,7 +141,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return EmptyTargetSource.class.hashCode() * 13 + ObjectUtils.nullSafeHashCode(this.targetClass);
+		return Objects.hash(getClass(), this.targetClass);
 	}
 
 	@Override

spring-aspects/src/test/java/org/springframework/cache/config/TestEntity.java

@@ -16,6 +16,8 @@
 
 package org.springframework.cache.config;
 
+import java.util.Objects;
+
 import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
@@ -42,7 +44,7 @@ public void setId(Long id) {
 
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.id);
+		return Objects.hashCode(this.id);
 	}
 
 	@Override

spring-beans/src/main/java/org/springframework/beans/BeanMetadataAttribute.java

@@ -90,7 +90,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return this.name.hashCode() * 29 + ObjectUtils.nullSafeHashCode(this.value);
+		return ObjectUtils.nullSafeHash(this.name, this.value);
 	}
 
 	@Override

spring-beans/src/main/java/org/springframework/beans/ExtendedBeanInfo.java

@@ -30,6 +30,7 @@
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Objects;
 import java.util.Set;
 import java.util.TreeSet;
 
@@ -345,7 +346,7 @@ public boolean equals(@Nullable Object other) {
 
 		@Override
 		public int hashCode() {
-			return (ObjectUtils.nullSafeHashCode(getReadMethod()) * 29 + ObjectUtils.nullSafeHashCode(getWriteMethod()));
+			return Objects.hash(getReadMethod(), getWriteMethod());
 		}
 
 		@Override
@@ -500,11 +501,8 @@ public boolean equals(@Nullable Object other) {
 
 		@Override
 		public int hashCode() {
-			int hashCode = ObjectUtils.nullSafeHashCode(getReadMethod());
-			hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getWriteMethod());
-			hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getIndexedReadMethod());
-			hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getIndexedWriteMethod());
-			return hashCode;
+			return Objects.hash(getReadMethod(), getWriteMethod(),
+					getIndexedReadMethod(), getIndexedWriteMethod());
 		}
 
 		@Override

spring-beans/src/main/java/org/springframework/beans/GenericTypeAwarePropertyDescriptor.java

@@ -20,6 +20,7 @@
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Method;
 import java.util.HashSet;
+import java.util.Objects;
 import java.util.Set;
 
 import org.apache.commons.logging.LogFactory;
@@ -30,7 +31,6 @@
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
-import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -172,10 +172,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = getBeanClass().hashCode();
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getReadMethod());
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getWriteMethod());
-		return hashCode;
+		return Objects.hash(getBeanClass(), getReadMethod(), getWriteMethod());
 	}
 
 }

spring-beans/src/main/java/org/springframework/beans/PropertyValue.java

@@ -197,7 +197,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return this.name.hashCode() * 29 + ObjectUtils.nullSafeHashCode(this.value);
+		return ObjectUtils.nullSafeHash(this.name, this.value);
 	}
 
 	@Override

spring-beans/src/main/java/org/springframework/beans/factory/InjectionPoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -20,6 +20,7 @@
 import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Field;
 import java.lang.reflect.Member;
+import java.util.Objects;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.lang.Nullable;
@@ -190,7 +191,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return (this.field != null ? this.field.hashCode() : ObjectUtils.nullSafeHashCode(this.methodParameter));
+		return Objects.hash(this.field, this.methodParameter);
 	}
 
 	@Override

spring-beans/src/main/java/org/springframework/beans/factory/config/BeanDefinitionHolder.java

@@ -173,10 +173,8 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = this.beanDefinition.hashCode();
-		hashCode = 29 * hashCode + this.beanName.hashCode();
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.aliases);
-		return hashCode;
+		return ObjectUtils.nullSafeHash(this.beanDefinition, this.beanName,
+				this.aliases);
 	}
 
 }

spring-beans/src/main/java/org/springframework/beans/factory/config/ConstructorArgumentValues.java

@@ -606,7 +606,7 @@ private boolean contentEquals(ValueHolder other) {
 		 * same content to reside in the same Set.
 		 */
 		private int contentHashCode() {
-			return ObjectUtils.nullSafeHashCode(this.value) * 29 + ObjectUtils.nullSafeHashCode(this.type);
+			return ObjectUtils.nullSafeHash(this.value, this.type);
 		}
 
 		/**

spring-beans/src/main/java/org/springframework/beans/factory/config/TypedStringValue.java

@@ -223,7 +223,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.value) * 29 + ObjectUtils.nullSafeHashCode(this.targetType);
+		return ObjectUtils.nullSafeHash(this.value, this.targetType);
 	}
 
 	@Override

spring-beans/src/main/java/org/springframework/beans/factory/support/MethodOverride.java

@@ -113,9 +113,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = ObjectUtils.nullSafeHashCode(this.methodName);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.source);
-		return hashCode;
+		return ObjectUtils.nullSafeHash(this.methodName, this.source);
 	}
 
 }

spring-context-support/src/main/java/org/springframework/mail/SimpleMailMessage.java

@@ -236,14 +236,8 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = ObjectUtils.nullSafeHashCode(this.from);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.replyTo);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.to);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.cc);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.bcc);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.sentDate);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.subject);
-		return hashCode;
+		return ObjectUtils.nullSafeHash(this.from, this.replyTo, this.to, this.cc,
+				this.bcc, this.sentDate, this.subject);
 	}
 
 	@Override

spring-context/src/main/java/org/springframework/context/event/AbstractApplicationEventMulticaster.java

@@ -21,6 +21,7 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Predicate;
@@ -404,7 +405,7 @@ public boolean equals(@Nullable Object other) {
 
 		@Override
 		public int hashCode() {
-			return this.eventType.hashCode() * 29 + ObjectUtils.nullSafeHashCode(this.sourceType);
+			return Objects.hash(this.eventType, this.sourceType);
 		}
 
 		@Override

spring-context/src/main/java/org/springframework/context/support/ApplicationListenerDetector.java

@@ -17,6 +17,7 @@
 package org.springframework.context.support;
 
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.commons.logging.Log;
@@ -28,7 +29,6 @@
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.event.ApplicationEventMulticaster;
 import org.springframework.lang.Nullable;
-import org.springframework.util.ObjectUtils;
 
 /**
  * {@code BeanPostProcessor} that detects beans which implement the {@code ApplicationListener}
@@ -120,7 +120,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.applicationContext);
+		return Objects.hashCode(this.applicationContext);
 	}
 
 }

spring-context/src/main/java/org/springframework/context/support/DefaultMessageSourceResolvable.java

@@ -179,10 +179,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = ObjectUtils.nullSafeHashCode(getCodes());
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getArguments());
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(getDefaultMessage());
-		return hashCode;
+		return ObjectUtils.nullSafeHash(getCode(), getArguments(), getDefaultMessage());
 	}
 
 }

spring-context/src/main/java/org/springframework/jmx/support/NotificationListenerHolder.java

@@ -167,11 +167,8 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		int hashCode = ObjectUtils.nullSafeHashCode(this.notificationListener);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.notificationFilter);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.handback);
-		hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.mappedObjectNames);
-		return hashCode;
+		return ObjectUtils.nullSafeHash(this.notificationListener, this.notificationFilter,
+				this.handback, this.mappedObjectNames);
 	}
 
 }

spring-context/src/testFixtures/java/org/springframework/context/testfixture/cache/beans/TestEntity.java

@@ -16,6 +16,8 @@
 
 package org.springframework.context.testfixture.cache.beans;
 
+import java.util.Objects;
+
 import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
@@ -38,7 +40,7 @@ public void setId(Long id) {
 
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.id);
+		return Objects.hashCode(this.id);
 	}
 
 	@Override

spring-core/src/main/java/org/springframework/core/annotation/RepeatableContainers.java

@@ -20,6 +20,7 @@
 import java.lang.annotation.Repeatable;
 import java.lang.reflect.Method;
 import java.util.Map;
+import java.util.Objects;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -91,7 +92,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(this.parent);
+		return Objects.hashCode(this.parent);
 	}
 
 

spring-core/src/main/java/org/springframework/core/convert/Property.java

@@ -22,6 +22,7 @@
 import java.lang.reflect.Method;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.Objects;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.lang.Nullable;
@@ -269,7 +270,7 @@ public boolean equals(@Nullable Object other) {
 
 	@Override
 	public int hashCode() {
-		return (ObjectUtils.nullSafeHashCode(this.objectType) * 31 + ObjectUtils.nullSafeHashCode(this.name));
+		return Objects.hash(this.objectType, this.name);
 	}
 
 }

spring-core/src/main/java/org/springframework/core/env/PropertySource.java

@@ -16,6 +16,8 @@
 
 package org.springframework.core.env;
 
+import java.util.Objects;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -147,7 +149,7 @@ public boolean equals(@Nullable Object other) {
 	 */
 	@Override
 	public int hashCode() {
-		return ObjectUtils.nullSafeHashCode(getName());
+		return Objects.hashCode(getName());
 	}
 
 	/**