GH-3990: Fix JsonPath native hint registration

Fixes #3990

Turns out just being on the classpath doesn’t make the type reachable.
If it’s only accessed reflectively then it’s not reachable.
This is exaclt what happened with our `JsonPathUtils` which is used via
reflection from SpEL when that calls its method via function reference

* Change `onReachableType()` logic for `com.jayway.jsonpath.JsonPath` type
to `ClassUtils.isPresent()` on `JsonPathUtils` reflection hint registration.

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/aot/CoreRuntimeHints.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 the original author or authors.
+ * Copyright 2022-2023 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.
@@ -34,7 +34,6 @@
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
 import org.springframework.aot.hint.SerializationHints;
-import org.springframework.aot.hint.TypeReference;
 import org.springframework.beans.factory.config.BeanExpressionContext;
 import org.springframework.context.SmartLifecycle;
 import org.springframework.integration.aggregator.MessageGroupProcessor;
@@ -66,6 +65,7 @@
 import org.springframework.messaging.ReactiveMessageHandler;
 import org.springframework.messaging.support.ErrorMessage;
 import org.springframework.messaging.support.GenericMessage;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -96,10 +96,10 @@ public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
 						Pausable.class)
 				.forEach(type -> reflectionHints.registerType(type, MemberCategory.INVOKE_PUBLIC_METHODS));
 
-		reflectionHints.registerType(JsonPathUtils.class,
-				builder ->
-						builder.onReachableType(TypeReference.of("com.jayway.jsonpath.JsonPath"))
-								.withMembers(MemberCategory.INVOKE_PUBLIC_METHODS));
+
+		if (ClassUtils.isPresent("com.jayway.jsonpath.JsonPath", classLoader)) {
+			reflectionHints.registerType(JsonPathUtils.class, MemberCategory.INVOKE_PUBLIC_METHODS);
+		}
 
 		// For #xpath() SpEL function
 		reflectionHints.registerTypeIfPresent(classLoader, "org.springframework.integration.xml.xpath.XPathUtils",