Add ifPresent utility methods on RuntimeHints

This commit adds a utility method to register a type for reflection if
it is available on the classpath. It also adds a method to register a
resource pattern if a given location is available.

Closes gh-28617

spring-core/src/main/java/org/springframework/aot/hint/ReflectionHints.java

@@ -30,6 +30,7 @@ import java.util.stream.Stream;
 
 import org.springframework.aot.hint.TypeHint.Builder;
 import org.springframework.lang.Nullable;
+import org.springframework.util.ClassUtils;
 
 /**
  * Gather the need for reflection at runtime.
@@ -95,6 +96,22 @@ public class ReflectionHints {
 		return registerType(TypeReference.of(type), typeHint);
 	}
 
+	/**
+	 * Register or customize reflection hints for the specified type if it
+	 * is available using the specified {@link ClassLoader}.
+	 * @param classLoader the classloader to use to check if the type is present
+	 * @param typeName the type to customize
+	 * @param typeHint a builder to further customize hints for that type
+	 * @return {@code this}, to facilitate method chaining
+	 */
+	public ReflectionHints registerTypeIfPresent(@Nullable ClassLoader classLoader,
+			String typeName, Consumer<TypeHint.Builder> typeHint) {
+		if (ClassUtils.isPresent(typeName, classLoader)) {
+			registerType(TypeReference.of(typeName), typeHint);
+		}
+		return this;
+	}
+
 	/**
 	 * Register or customize reflection hints for the types defined by the
 	 * specified list of {@link TypeReference type references}. The specified

spring-core/src/main/java/org/springframework/aot/hint/ResourceHints.java

@@ -65,6 +65,24 @@ public class ResourceHints {
 		return this.resourceBundleHints.stream();
 	}
 
+	/**
+	 * Register a pattern if the given {@code location} is available on the
+	 * classpath. This delegates to {@link ClassLoader#getResource(String)}
+	 * which validates directories as well. The location is not included in
+	 * the hint.
+	 * @param classLoader the classloader to use
+	 * @param location a '/'-separated path name that should exist
+	 * @param resourceHint a builder to customize the resource pattern
+	 * @return {@code this}, to facilitate method chaining
+	 */
+	public ResourceHints registerPatternIfPresent(@Nullable ClassLoader classLoader, String location, Consumer<ResourcePatternHints.Builder> resourceHint) {
+		ClassLoader classLoaderToUse = (classLoader != null) ? classLoader : getClass().getClassLoader();
+		if (classLoaderToUse.getResource(location) != null) {
+			registerPattern(resourceHint);
+		}
+		return this;
+	}
+
 	/**
 	 * Register that the resources matching the specified pattern should be
 	 * made available at runtime.