Deprecate StandardMetadata constructors

Deprecate the public `StandardMetadata` constructors to make it clearer
that these classes should not be instantiated directly. A new
`AnnotationMetadata.introspect` factory method has been added which
can now be used to obtain instances.

This change will allow use to make the constructors package private
and drop the `nestedAnnotationsAsMap` parameter in a future release.

Closes gh-22906

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

@@ -115,4 +115,16 @@ public interface AnnotationMetadata extends ClassMetadata, AnnotatedTypeMetadata
 	 */
 	Set<MethodMetadata> getAnnotatedMethods(String annotationName);
 
+
+	/**
+	 * Factory method to create a new {@link AnnotationMetadata} instance
+	 * for the given class using standard reflection.
+	 * @param type the class to introspect
+	 * @return a new {@link AnnotationMetadata} instance
+	 * @since 5.2
+	 */
+	static AnnotationMetadata introspect(Class<?> type) {
+		return StandardAnnotationMetadata.from(type);
+	}
+
 }

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

@@ -26,6 +26,7 @@ import java.util.Set;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationFilter;
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.annotation.MergedAnnotation;
 import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.core.annotation.MergedAnnotations.SearchStrategy;
 import org.springframework.core.annotation.RepeatableContainers;
@@ -56,7 +57,9 @@ public class StandardAnnotationMetadata extends StandardClassMetadata implements
 	 * Create a new {@code StandardAnnotationMetadata} wrapper for the given Class.
 	 * @param introspectedClass the Class to introspect
 	 * @see #StandardAnnotationMetadata(Class, boolean)
+	 * @deprecated since 5.2 in favor of the factory method {@link AnnotationMetadata#introspect(Class)}
 	 */
+	@Deprecated
 	public StandardAnnotationMetadata(Class<?> introspectedClass) {
 		this(introspectedClass, false);
 	}
@@ -71,7 +74,12 @@ public class StandardAnnotationMetadata extends StandardClassMetadata implements
 	 * {@link org.springframework.core.annotation.AnnotationAttributes} for compatibility
 	 * with ASM-based {@link AnnotationMetadata} implementations
 	 * @since 3.1.1
+	 * @deprecated since 5.2 in favor of the factory method {@link AnnotationMetadata#introspect(Class)}.
+	 * Use {@link MergedAnnotation#asMap(org.springframework.core.annotation.MergedAnnotation.Adapt...) MergedAnnotation.asMap}
+	 * from {@link #getAnnotations()} rather than {@link #getAnnotationAttributes(String)}
+	 * if {@code nestedAnnotationsAsMap} is {@code false}
 	 */
+	@Deprecated
 	public StandardAnnotationMetadata(Class<?> introspectedClass, boolean nestedAnnotationsAsMap) {
 		super(introspectedClass);
 		this.mergedAnnotations = MergedAnnotations.from(introspectedClass,
@@ -138,6 +146,7 @@ public class StandardAnnotationMetadata extends StandardClassMetadata implements
 	}
 
 	@Override
+	@SuppressWarnings("deprecation")
 	public Set<MethodMetadata> getAnnotatedMethods(String annotationName) {
 		Set<MethodMetadata> annotatedMethods = null;
 		if (AnnotationUtils.isCandidateClass(getIntrospectedClass(), annotationName)) {
@@ -164,4 +173,9 @@ public class StandardAnnotationMetadata extends StandardClassMetadata implements
 				AnnotatedElementUtils.isAnnotated(method, annotationName);
 	}
 
+
+	static AnnotationMetadata from(Class<?> introspectedClass) {
+		return new StandardAnnotationMetadata(introspectedClass, true);
+	}
+
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -38,7 +38,9 @@ public class StandardClassMetadata implements ClassMetadata {
 	/**
 	 * Create a new StandardClassMetadata wrapper for the given Class.
 	 * @param introspectedClass the Class to introspect
+	 * @deprecated since 5.2 in favor of {@link StandardAnnotationMetadata}
 	 */
+	@Deprecated
 	public StandardClassMetadata(Class<?> introspectedClass) {
 		Assert.notNull(introspectedClass, "Class must not be null");
 		this.introspectedClass = introspectedClass;

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

@@ -51,7 +51,9 @@ public class StandardMethodMetadata implements MethodMetadata {
 	/**
 	 * Create a new StandardMethodMetadata wrapper for the given Method.
 	 * @param introspectedMethod the Method to introspect
+	 * @deprecated since 5.2 in favor of obtaining instances via {@link AnnotationMetadata}
 	 */
+	@Deprecated
 	public StandardMethodMetadata(Method introspectedMethod) {
 		this(introspectedMethod, false);
 	}
@@ -66,7 +68,9 @@ public class StandardMethodMetadata implements MethodMetadata {
 	 * {@link org.springframework.core.annotation.AnnotationAttributes} for compatibility
 	 * with ASM-based {@link AnnotationMetadata} implementations
 	 * @since 3.1.1
+	 * @deprecated since 5.2 in favor of obtaining instances via {@link AnnotationMetadata}
 	 */
+	@Deprecated
 	public StandardMethodMetadata(Method introspectedMethod, boolean nestedAnnotationsAsMap) {
 		Assert.notNull(introspectedMethod, "Method must not be null");
 		this.introspectedMethod = introspectedMethod;