Clarify the comma in "spring.config.activate.on-profile" value and add test

See spring-cloud/spring-cloud-commons#1416 (comment)

Signed-off-by: Yanming Zhou <[email protected]>

Author: quaff

spring-boot-project/spring-boot-docs/src/docs/antora/modules/how-to/pages/properties-and-configuration.adoc

@@ -291,6 +291,8 @@ In the preceding example, the default port is 9000.
 However, if the Spring profile called '`development`' is active, then the port is 9001.
 If '`production`' is active, then the port is 0.
 
+NOTE: The comma in profile value is equivalent to `|`, `profile1,profile2` is equivalent to `profile1|profile2` not `profile1&profile2`.
+
 NOTE: The documents are merged in the order in which they are encountered.
 Later values override earlier values.
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -200,6 +200,17 @@ void isActiveAgainstBoundDataWhenCloudPlatformDoesntMatch() {
 		assertThat(properties.isActive(context)).isFalse();
 	}
 
+	@Test
+	void isActiveAgainstBoundDataWhenProfilesMatchCommaSeparatedList() {
+		MapConfigurationPropertySource source = new MapConfigurationPropertySource();
+		source.put("spring.config.activate.on-profile", "a&b,nonexistent");
+		Binder binder = new Binder(source);
+		ConfigDataProperties properties = ConfigDataProperties.get(binder);
+		ConfigDataActivationContext context = new ConfigDataActivationContext(NULL_CLOUD_PLATFORM,
+				createTestProfiles());
+		assertThat(properties.isActive(context)).isTrue();
+	}
+
 	@Test
 	void getImportOriginWhenCommaListReturnsOrigin() {
 		MapConfigurationPropertySource source = new MapConfigurationPropertySource();