Use canonical names in error messages in annotation processing

Prior to this commit, we invoked `Class.getName()` when building error
messages during annotation processing, resulting in exceptions like the
following which use binary names for nested types and arrays.

  Attribute 'chars' in annotation
  org.springframework.core.annotation.AnnotationUtilsTests$CharsContainer
  should be compatible with [C but a [I value was returned

This commit switches to canonical names in error messages in annotation
processing, resulting in improved such errors messages such as the
following.

  Attribute 'chars' in annotation
  org.springframework.core.annotation.AnnotationUtilsTests.CharsContainer
  should be compatible with char[] but a int[] value was returned

In addition, this commit introduces a new getCanonicalName(Class) method
in ClassUtils, which has effectively been extracted from the following
classes where this functionality was previously duplicated.

- AttributeMethods
- SynthesizedMergedAnnotationInvocationHandler
- TypeDescriptor
- DefaultRetryPolicy
- ReflectiveIndexAccessor

Closes gh-36607

spring-core-test/src/main/java/org/springframework/aot/agent/MethodReference.java

@@ -20,6 +20,8 @@ import java.util.Objects;
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.util.ClassUtils;
+
 /**
  * Reference to a Java method, identified by its owner class and the method name.
  *
@@ -43,7 +45,7 @@ public final class MethodReference {
 	}
 
 	public static MethodReference of(Class<?> klass, String methodName) {
-		return new MethodReference(klass.getCanonicalName(), methodName);
+		return new MethodReference(ClassUtils.getCanonicalName(klass), methodName);
 	}
 
 	/**

spring-core-test/src/main/java/org/springframework/aot/agent/RecordedInvocation.java

@@ -25,6 +25,7 @@ import org.jspecify.annotations.Nullable;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.TypeReference;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
  * Record of an invocation of a method relevant to {@link org.springframework.aot.hint.RuntimeHints}.
@@ -181,7 +182,7 @@ public final class RecordedInvocation {
 		else {
 			Class<?> instanceType = (getInstance() instanceof Class<?> clazz) ? clazz : getInstance().getClass();
 			return "<%s> invocation of <%s> on type <%s> with arguments %s".formatted(
-					getHintType().hintClassName(), getMethodReference(), instanceType.getCanonicalName(), getArguments());
+					getHintType().hintClassName(), getMethodReference(), ClassUtils.getCanonicalName(instanceType), getArguments());
 		}
 	}