Allow exclude only health groups

Closes gh-22053

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/health/IncludeExcludeGroupMemberPredicate.java

@@ -44,7 +44,7 @@ class IncludeExcludeGroupMemberPredicate implements Predicate<String> {
 	}
 
 	private boolean isIncluded(String name) {
-		return this.include.contains("*") || this.include.contains(clean(name));
+		return this.include.isEmpty() || this.include.contains("*") || this.include.contains(clean(name));
 	}
 
 	private boolean isExcluded(String name) {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/health/IncludeExcludeGroupMemberPredicateTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.autoconfigure.health;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Set;
 import java.util.function.Predicate;
@@ -29,13 +30,14 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link IncludeExcludeGroupMemberPredicate}.
  *
  * @author Phillip Webb
+ * @author Madhura Bhave
  */
 class IncludeExcludeGroupMemberPredicateTests {
 
 	@Test
-	void testWhenEmptyIncludeAndExcludeRejectsAll() {
+	void testWhenEmptyIncludeAndExcludeAcceptsAll() {
 		Predicate<String> predicate = new IncludeExcludeGroupMemberPredicate(null, null);
-		assertThat(predicate).rejects("a", "b", "c");
+		assertThat(predicate).accepts("a", "b", "c");
 	}
 
 	@Test
@@ -44,6 +46,12 @@ class IncludeExcludeGroupMemberPredicateTests {
 		assertThat(predicate).accepts("a", "b", "c");
 	}
 
+	@Test
+	void testWhenEmptyIncludeAndNonEmptyExcludeAcceptsAllButExclude() {
+		Predicate<String> predicate = new IncludeExcludeGroupMemberPredicate(null, Collections.singleton("c"));
+		assertThat(predicate).accepts("a", "b");
+	}
+
 	@Test
 	void testWhenStarIncludeAndSpecificExcludeDoesNotAcceptExclude() {
 		Predicate<String> predicate = include("*").exclude("c");

spring-boot-project/spring-boot-docs/src/docs/asciidoc/production-ready-features.adoc

@@ -881,6 +881,13 @@ For example, to create a group that includes only database indicators you can de
 
 You can then check the result by hitting `http://localhost:8080/actuator/health/custom`.
 
+Similarly, to create a group that excludes the database indicators from the group and includes all the other indicators, you can define the following:
+
+[source,properties,indent=0,configprops]
+----
+	management.endpoint.health.group.custom.exclude=db
+----
+
 By default groups will inherit the same `StatusAggregator` and `HttpCodeStatusMapper` settings as the system health, however, these can also be defined on a per-group basis.
 It's also possible to override the `show-details` and `roles` properties if required: