Improve log message with active profiles

Closes gh-4612

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

@@ -650,7 +650,9 @@ public class SpringApplication {
 		if (log.isInfoEnabled()) {
 			String[] activeProfiles = context.getEnvironment().getActiveProfiles();
 			if (ObjectUtils.isEmpty(activeProfiles)) {
-				log.info("No profiles are active");
+				String[] defaultProfiles = context.getEnvironment().getDefaultProfiles();
+				log.info("No active profile set, falling back to default profiles: "
+						+ StringUtils.arrayToCommaDelimitedString(defaultProfiles));
 			}
 			else {
 				log.info("The following profiles are active: "

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

@@ -222,7 +222,8 @@ public class SpringApplicationTests {
 		SpringApplication application = new SpringApplication(ExampleConfig.class);
 		application.setWebEnvironment(false);
 		this.context = application.run();
-		assertThat(this.output.toString(), containsString("No profiles are active"));
+		assertThat(this.output.toString(), containsString(
+				"No active profile set, falling back to default profiles: default"));
 	}
 
 	@Test