Cache key classes implement Comparable and consistently provide a toString representation

Issue: SPR-14017

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

@@ -1802,7 +1802,7 @@ public abstract class AnnotationUtils {
 	/**
 	 * Cache key for the AnnotatedElement cache.
 	 */
-	private static class AnnotationCacheKey {
+	private static final class AnnotationCacheKey implements Comparable<AnnotationCacheKey> {
 
 		private final AnnotatedElement element;
 
@@ -1829,6 +1829,20 @@ public abstract class AnnotationUtils {
 		public int hashCode() {
 			return (this.element.hashCode() * 29 + this.annotationType.hashCode());
 		}
+
+		@Override
+		public String toString() {
+			return "@" + this.annotationType + " on " + this.element;
+		}
+
+		@Override
+		public int compareTo(AnnotationCacheKey other) {
+			int result = this.element.toString().compareTo(other.element.toString());
+			if (result == 0) {
+				result = this.annotationType.getName().compareTo(other.annotationType.getName());
+			}
+			return result;
+		}
 	}
 
 

spring-core/src/main/java/org/springframework/core/convert/support/GenericConversionService.java

@@ -435,7 +435,7 @@ public class GenericConversionService implements ConfigurableConversionService {
 	/**
 	 * Key for use with the converter cache.
 	 */
-	private static final class ConverterCacheKey {
+	private static final class ConverterCacheKey implements Comparable<ConverterCacheKey> {
 
 		private final TypeDescriptor sourceType;
 
@@ -470,6 +470,17 @@ public class GenericConversionService implements ConfigurableConversionService {
 			return ("ConverterCacheKey [sourceType = " + this.sourceType +
 					", targetType = " + this.targetType + "]");
 		}
+
+		@Override
+		public int compareTo(ConverterCacheKey other) {
+			int result = this.sourceType.getResolvableType().toString().compareTo(
+					other.sourceType.getResolvableType().toString());
+			if (result == 0) {
+				result = this.targetType.getResolvableType().toString().compareTo(
+						other.targetType.getResolvableType().toString());
+			}
+			return result;
+		}
 	}