Prevent 'Recursive update' exceptions with Restarter

Update `Restarter` to prevent 'Recursive update' `IllegalStateException`
from being thrown. Calls to `objectFactory.getObject()` now happen
outside of `computeIfAbsent`.

Fixes gh-41571

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/Restarter.java

@@ -440,7 +440,12 @@ public class Restarter {
 	}
 
 	public Object getOrAddAttribute(String name, final ObjectFactory<?> objectFactory) {
-		return this.attributes.computeIfAbsent(name, (ignore) -> objectFactory.getObject());
+		Object value = this.attributes.get(name);
+		if (value == null) {
+			value = objectFactory.getObject();
+			this.attributes.put(name, value);
+		}
+		return value;
 	}
 
 	public Object removeAttribute(String name) {

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/restart/RestarterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -145,15 +145,28 @@ class RestarterTests {
 	}
 
 	@Test
-	@SuppressWarnings("rawtypes")
 	void getOrAddAttributeWithExistingAttribute() {
 		Restarter.getInstance().getOrAddAttribute("x", () -> "abc");
-		ObjectFactory objectFactory = mock(ObjectFactory.class);
+		ObjectFactory<?> objectFactory = mock(ObjectFactory.class);
 		Object attribute = Restarter.getInstance().getOrAddAttribute("x", objectFactory);
 		assertThat(attribute).isEqualTo("abc");
 		then(objectFactory).shouldHaveNoInteractions();
 	}
 
+	@Test
+	void getOrAddAttributeWithRecursion() {
+		Restarter restarter = Restarter.getInstance();
+		Object added = restarter.getOrAddAttribute("postgresContainer", () -> {
+			restarter.getOrAddAttribute("rabbitContainer", () -> "def");
+			return "abc";
+		});
+		ObjectFactory<?> objectFactory = mock(ObjectFactory.class);
+		assertThat(added).isEqualTo("abc");
+		assertThat(restarter.getOrAddAttribute("postgresContainer", objectFactory)).isEqualTo("abc");
+		assertThat(restarter.getOrAddAttribute("rabbitContainer", objectFactory)).isEqualTo("def");
+		then(objectFactory).shouldHaveNoInteractions();
+	}
+
 	@Test
 	void getThreadFactory() throws Exception {
 		final ClassLoader parentLoader = Thread.currentThread().getContextClassLoader();