Allow spring.main.sources to override only if uninitialized

The problem this change fixes is that spring.main.sources would always
be bound to SpringApplication.sources when provided in a properties file
even if SpringApplication.run() is called directly with sources. This
led to confusion with users saying that their sources were not working
where in fact they weren't even being used.

There would be more than one way to approach this problem, but we
have chosen for now to ignore spring.main.sources completely
if the SpringApplication constructor was already called with
explicit non-empty sources. It might be preferable, if possible,
to only ignore its value in an external properties file (allowing
command line or System properties to override). If we want to change
the behaviour again, I suggest a new story should be created.

[Fixes #54185750] [bs-255]

spring-boot/src/main/java/org/springframework/boot/BeanDefinitionLoader.java

@@ -155,7 +155,8 @@ class BeanDefinitionLoader {
 
 	private int load(CharSequence source) {
 		try {
-			return load(Class.forName(source.toString()));
+			// Use class utils so that period separated nested class names work
+			return load(ClassUtils.forName(source.toString(), null));
 		}
 		catch (ClassNotFoundException ex) {
 			// swallow exception and continue

spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -161,6 +161,8 @@ public class SpringApplication {
 
 	private String[] defaultCommandLineArgs;
 
+	private boolean sourcesInitialized = false;
+
 	/**
 	 * Crate a new {@link SpringApplication} instance. The application context will load
 	 * beans from the specified sources (see {@link SpringApplication class-level}
@@ -190,7 +192,8 @@ public class SpringApplication {
 	}
 
 	private void initialize(Object[] sources) {
-		if (sources != null) {
+		if (sources != null && sources.length > 0) {
+			this.sourcesInitialized = true;
 			this.sources.addAll(Arrays.asList(sources));
 		}
 		this.webEnvironment = deduceWebEnvironment();
@@ -576,6 +579,9 @@ public class SpringApplication {
 	 * @see #SpringApplication(Object...)
 	 */
 	public void setSources(Set<Object> sources) {
+		if (this.sourcesInitialized) {
+			return;
+		}
 		Assert.notNull(sources, "Sources must not be null");
 		this.sources = new LinkedHashSet<Object>(sources);
 	}

spring-boot/src/test/java/org/springframework/boot/OverrideSourcesTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2012-2013 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot;
+
+import org.junit.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Dave Syer
+ */
+public class OverrideSourcesTests {
+
+	@Test
+	public void beanInjectedToMainConfiguration() {
+		ApplicationContext context = SpringApplication.run(
+				new Object[] { MainConfiguration.class },
+				new String[] { "--spring.main.web_environment=false" });
+		assertEquals("foo", context.getBean(Service.class).bean.name);
+	}
+
+	@Test
+	public void primaryBeanInjectedProvingSourcesNotOverridden() {
+		ApplicationContext context = SpringApplication
+				.run(new Object[] { MainConfiguration.class, TestConfiguration.class },
+						new String[] { "--spring.main.web_environment=false",
+								"--spring.main.sources=org.springframework.boot.OverrideSourcesTests.MainConfiguration" });
+		assertEquals("bar", context.getBean(Service.class).bean.name);
+	}
+
+	@Configuration
+	protected static class TestConfiguration {
+
+		@Bean
+		@Primary
+		public TestBean another() {
+			return new TestBean("bar");
+		}
+
+	}
+
+	@Configuration
+	protected static class MainConfiguration {
+
+		@Bean
+		public TestBean first() {
+			return new TestBean("foo");
+		}
+
+		@Bean
+		public Service Service() {
+			return new Service();
+		}
+
+	}
+
+	protected static class Service {
+		@Autowired
+		private TestBean bean;
+	}
+
+	protected static class TestBean {
+
+		private String name;
+
+		public TestBean(String name) {
+			this.name = name;
+		}
+
+	}
+}