Add convenience methods to SanitizingFunction

Add a `sanitizeValue()` factory method and `if...` methods that can
be used to quickly build a `SanitizingFunction`.

Closes gh-39243

Author: philwebb

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.endpoint;
 
+import java.util.Locale;
+
 import org.springframework.core.env.PropertySource;
 
 /**
@@ -36,6 +38,8 @@ public final class SanitizableData {
 
 	private final String key;
 
+	private String lowerCaseKey;
+
 	private final Object value;
 
 	/**
@@ -67,6 +71,20 @@ public String getKey() {
 		return this.key;
 	}
 
+	/**
+	 * Return the key as a lowercase value.
+	 * @return the key as a lowercase value
+	 * @since 3.5.0
+	 */
+	public String getLowerCaseKey() {
+		String result = this.lowerCaseKey;
+		if (result == null && this.key != null) {
+			result = this.key.toLowerCase(Locale.getDefault());
+			this.lowerCaseKey = result;
+		}
+		return result;
+	}
+
 	/**
 	 * Return the value of the data.
 	 * @return the data value

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

@@ -72,7 +72,7 @@ public Object sanitize(SanitizableData data, boolean showUnsanitized) {
 			return SanitizableData.SANITIZED_VALUE;
 		}
 		for (SanitizingFunction sanitizingFunction : this.sanitizingFunctions) {
-			data = sanitizingFunction.apply(data);
+			data = sanitizingFunction.applyUnlessFiltered(data);
 			Object sanitizedValue = data.getValue();
 			if (!value.equals(sanitizedValue)) {
 				return sanitizedValue;