Test that empty property files can be used

Add an additional test to ensure that empty property files do not
throw ConfigDataLocationNotFoundException exceptions.

See gh-24499
See gh-24515

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentPostProcessorIntegrationTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.context.config;
 
 import java.io.File;
 import java.io.FileOutputStream;
+import java.io.IOException;
 import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -56,6 +57,7 @@ import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
+import org.springframework.util.FileCopyUtils;
 import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -544,6 +546,15 @@ class ConfigDataEnvironmentPostProcessorIntegrationTests {
 				.run("--spring.config.location=" + StringUtils.cleanPath(location.getAbsolutePath()) + "/"));
 	}
 
+	@Test
+	void runWhenConfigLocationHasNonOptionalEmptyFileDoesNotThrowException() throws IOException {
+		File location = new File(this.temp, "application.properties");
+		FileCopyUtils.copy(new byte[0], location);
+		assertThatNoException()
+				.isThrownBy(() -> this.application.run("--spring.config.location=classpath:/application.properties,"
+						+ StringUtils.cleanPath(location.getAbsolutePath())));
+	}
+
 	@Test
 	@Disabled("Disabled until spring.profiles suppport is dropped")
 	void runWhenUsingInvalidPropertyThrowsException() {