Implement equals, hashCode, & toString in BeanMethod and *Metadata types

Prior to this commit, ConfigurationClass implemented equals(),
hashCode(), and toString(), but BeanMethod did not.

This commit introduces equals(), hashCode(), and toString()
implementations in BeanMethod for consistency with ConfigurationClass
to make it possible to use BeanMethod instances to index additional
metadata as well.

In order to properly implement equals() in BeanMethod, the method
argument types are required, but these are not directly available in
BeanMethod. However, they are available via ASM when processing @Bean
methods. This commit therefore implements equals(), hashCode(), and
toString() in SimpleMethodMetadata which BeanMethod delegates to.

For completeness, this commit also implements equals(), hashCode(), and
toString() in StandardClassMetadata, StandardMethodMetadata, and
SimpleAnnotationMetadata.

Closes gh-27076

spring-core/src/main/java/org/springframework/core/type/StandardClassMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -28,6 +28,7 @@ import org.springframework.util.StringUtils;
  * to introspect a given {@code Class}.
  *
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 2.5
  */
 public class StandardClassMetadata implements ClassMetadata {
@@ -119,4 +120,20 @@ public class StandardClassMetadata implements ClassMetadata {
 		return StringUtils.toStringArray(memberClassNames);
 	}
 
+	@Override
+	public boolean equals(@Nullable Object obj) {
+		return ((this == obj) || ((obj instanceof StandardClassMetadata) &&
+				getIntrospectedClass().equals(((StandardClassMetadata) obj).getIntrospectedClass())));
+	}
+
+	@Override
+	public int hashCode() {
+		return getIntrospectedClass().hashCode();
+	}
+
+	@Override
+	public String toString() {
+		return getClassName();
+	}
+
 }

spring-core/src/main/java/org/springframework/core/type/StandardMethodMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -36,6 +36,7 @@ import org.springframework.util.MultiValueMap;
  * @author Mark Pollack
  * @author Chris Beams
  * @author Phillip Webb
+ * @author Sam Brannen
  * @since 3.0
  */
 public class StandardMethodMetadata implements MethodMetadata {
@@ -150,4 +151,20 @@ public class StandardMethodMetadata implements MethodMetadata {
 				annotationName, classValuesAsString, false);
 	}
 
+	@Override
+	public boolean equals(@Nullable Object obj) {
+		return ((this == obj) || ((obj instanceof StandardMethodMetadata) &&
+				this.introspectedMethod.equals(((StandardMethodMetadata) obj).introspectedMethod)));
+	}
+
+	@Override
+	public int hashCode() {
+		return this.introspectedMethod.hashCode();
+	}
+
+	@Override
+	public String toString() {
+		return this.introspectedMethod.toString();
+	}
+
 }

spring-core/src/main/java/org/springframework/core/type/classreading/SimpleAnnotationMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -31,6 +31,7 @@ import org.springframework.lang.Nullable;
  * {@link SimpleAnnotationMetadataReadingVisitor}.
  *
  * @author Phillip Webb
+ * @author Sam Brannen
  * @since 5.2
  */
 final class SimpleAnnotationMetadata implements AnnotationMetadata {
@@ -156,4 +157,20 @@ final class SimpleAnnotationMetadata implements AnnotationMetadata {
 		return this.annotations;
 	}
 
+	@Override
+	public boolean equals(@Nullable Object obj) {
+		return ((this == obj) || ((obj instanceof SimpleAnnotationMetadata) &&
+				this.className.equals(((SimpleAnnotationMetadata) obj).className)));
+	}
+
+	@Override
+	public int hashCode() {
+		return this.className.hashCode();
+	}
+
+	@Override
+	public String toString() {
+		return this.className;
+	}
+
 }

spring-core/src/main/java/org/springframework/core/type/classreading/SimpleMethodMetadata.java

@@ -19,11 +19,13 @@ package org.springframework.core.type.classreading;
 import org.springframework.asm.Opcodes;
 import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.core.type.MethodMetadata;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link MethodMetadata} created from a {@link SimpleMethodMetadataReadingVisitor}.
  *
  * @author Phillip Webb
+ * @author Sam Brannen
  * @since 5.2
  */
 final class SimpleMethodMetadata implements MethodMetadata {
@@ -36,16 +38,20 @@ final class SimpleMethodMetadata implements MethodMetadata {
 
 	private final String returnTypeName;
 
+	// The source implements equals(), hashCode(), and toString() for the underlying method.
+	private final Object source;
+
 	private final MergedAnnotations annotations;
 
 
-	public SimpleMethodMetadata(String methodName, int access, String declaringClassName,
-			String returnTypeName, MergedAnnotations annotations) {
+	SimpleMethodMetadata(String methodName, int access, String declaringClassName,
+			String returnTypeName, Object source, MergedAnnotations annotations) {
 
 		this.methodName = methodName;
 		this.access = access;
 		this.declaringClassName = declaringClassName;
 		this.returnTypeName = returnTypeName;
+		this.source = source;
 		this.annotations = annotations;
 	}
 
@@ -94,4 +100,20 @@ final class SimpleMethodMetadata implements MethodMetadata {
 		return this.annotations;
 	}
 
+	@Override
+	public boolean equals(@Nullable Object obj) {
+		return ((this == obj) || ((obj instanceof SimpleMethodMetadata) &&
+				this.source.equals(((SimpleMethodMetadata) obj).source)));
+	}
+
+	@Override
+	public int hashCode() {
+		return this.source.hashCode();
+	}
+
+	@Override
+	public String toString() {
+		return this.source.toString();
+	}
+
 }

spring-core/src/main/java/org/springframework/core/type/classreading/SimpleMethodMetadataReadingVisitor.java

@@ -81,8 +81,8 @@ final class SimpleMethodMetadataReadingVisitor extends MethodVisitor {
 		if (!this.annotations.isEmpty()) {
 			String returnTypeName = Type.getReturnType(this.descriptor).getClassName();
 			MergedAnnotations annotations = MergedAnnotations.of(this.annotations);
-			SimpleMethodMetadata metadata = new SimpleMethodMetadata(this.methodName,
-					this.access, this.declaringClassName, returnTypeName, annotations);
+			SimpleMethodMetadata metadata = new SimpleMethodMetadata(this.methodName, this.access,
+					this.declaringClassName, returnTypeName, getSource(), annotations);
 			this.consumer.accept(metadata);
 		}
 	}