Search for main methods from the bottom of the stack

Update `MainMethod` to search from the bottom of the stack rather than
the start. Prior to this commit, an incorrect `main` method would be
found if more than one `main` was in the stack.

Fixes gh-35214

Author: philwebb

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -40,7 +40,9 @@ class MainMethod {
 	}
 
 	private Method getMainMethod(Thread thread) {
-		for (StackTraceElement element : thread.getStackTrace()) {
+		StackTraceElement[] stackTrace = thread.getStackTrace();
+		for (int i = stackTrace.length - 1; i >= 0; i--) {
+			StackTraceElement element = stackTrace[i];
 			if ("main".equals(element.getMethodName())) {
 				Method method = getMainMethod(element);
 				if (method != null) {

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

@@ -56,6 +56,14 @@ void validMainMethod() throws Exception {
 		assertThat(method.getDeclaringClassName()).isEqualTo(this.actualMain.getDeclaringClass().getName());
 	}
 
+	@Test // gh-35214
+	void nestedMainMethod() throws Exception {
+		MainMethod method = new TestThread(Nested::main).test();
+		Method nestedMain = Nested.class.getMethod("main", String[].class);
+		assertThat(method.getMethod()).isEqualTo(nestedMain);
+		assertThat(method.getDeclaringClassName()).isEqualTo(nestedMain.getDeclaringClass().getName());
+	}
+
 	@Test
 	void missingArgsMainMethod() {
 		assertThatIllegalStateException().isThrownBy(() -> new TestThread(MissingArgs::main).test())
@@ -114,6 +122,15 @@ private static void someOtherMethod() {
 
 	}
 
+	public static class Nested {
+
+		public static void main(String... args) {
+			mainMethod.set(new MainMethod());
+			Valid.main(args);
+		}
+
+	}
+
 	public static class MissingArgs {
 
 		public static void main() {