Support overriding the default SanitizingFunction

See gh-30006

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/Sanitizer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -184,13 +184,18 @@ public class Sanitizer {
 	 * @since 2.6.0
 	 */
 	public Object sanitize(SanitizableData data) {
-		if (data.getValue() == null) {
+		Object value = data.getValue();
+		if (value == null) {
 			return null;
 		}
 		for (SanitizingFunction sanitizingFunction : this.sanitizingFunctions) {
 			data = sanitizingFunction.apply(data);
+			Object sanitizedValue = data.getValue();
+			if (!value.equals(sanitizedValue)) {
+				return sanitizedValue;
+			}
 		}
-		return data.getValue();
+		return value;
 	}
 
 	private boolean keyIsUriWithUserInfo(Pattern pattern) {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpointTests.java

@@ -293,7 +293,7 @@ class ConfigurationPropertiesReportEndpointTests {
 		new ApplicationContextRunner().withUserConfiguration(CustomSanitizingEndpointConfig.class,
 				SanitizingFunctionConfiguration.class, TestPropertiesConfiguration.class)
 				.run(assertProperties("test", (properties) -> {
-					assertThat(properties.get("dbPassword")).isEqualTo("******");
+					assertThat(properties.get("dbPassword")).isEqualTo("$$$");
 					assertThat(properties.get("myTestProperty")).isEqualTo("$$$");
 				}));
 	}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/SanitizerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -16,7 +16,9 @@
 
 package org.springframework.boot.actuate.endpoint;
 
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Test;
@@ -87,6 +89,39 @@ class SanitizerTests {
 		assertThat(sanitizer.sanitize(hello)).isEqualTo("abc");
 	}
 
+	@Test
+	void overridingDefaultSanitizingFunction() {
+		Sanitizer sanitizer = new Sanitizer(Collections.singletonList((data) -> {
+			if (data.getKey().equals("password")) {
+				return data.withValue("------");
+			}
+			return data;
+		}));
+		SanitizableData password = new SanitizableData(null, "password", "123456");
+		assertThat(sanitizer.sanitize(password)).isEqualTo("------");
+	}
+
+	@Test
+	void whenValueSanitizedLaterSanitizingFunctionsShouldBeSkipped() {
+		final String sameKey = "custom";
+		List<SanitizingFunction> sanitizingFunctions = new ArrayList<>();
+		sanitizingFunctions.add((data) -> {
+			if (data.getKey().equals(sameKey)) {
+				return data.withValue("------");
+			}
+			return data;
+		});
+		sanitizingFunctions.add((data) -> {
+			if (data.getKey().equals(sameKey)) {
+				return data.withValue("******");
+			}
+			return data;
+		});
+		Sanitizer sanitizer = new Sanitizer(sanitizingFunctions);
+		SanitizableData custom = new SanitizableData(null, sameKey, "123456");
+		assertThat(sanitizer.sanitize(custom)).isEqualTo("------");
+	}
+
 	@ParameterizedTest(name = "key = {0}")
 	@MethodSource("matchingUriUserInfoKeys")
 	void uriWithSingleValueWithPasswordShouldBeSanitized(String key) {