Document the semantic of using multiple profile expressions

This commit clarifies the semantic of declaring multiple profile
expression with the "spring.config.activate.on-profile" property.

See gh-44866

Signed-off-by: Yanming Zhou <zhouyanming@gmail.com>

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/features/external-config.adoc

@@ -545,7 +545,9 @@ The following activation properties are available:
 | Property | Note
 
 | `on-profile`
-| A profile expression that must match for the document to be active.
+| A profile expression that must match for the document to be active,
+or a list of profile expressions of which at least one must match for the document to be active.
+Please note comma-separated list such as `foo,bar` is equal to `foo\|bar` instead of `foo&bar`.
 
 | `on-cloud-platform`
 | The javadoc:org.springframework.boot.cloud.CloudPlatform[] that must be detected for the document to be active.

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 @@ class ConfigDataPropertiesTests {
 		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();