Add Duration support in /configprops endpoint

See gh-16539

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpoint.java

@@ -41,6 +41,7 @@ import com.fasterxml.jackson.databind.ser.PropertyWriter;
 import com.fasterxml.jackson.databind.ser.SerializerFactory;
 import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter;
 import com.fasterxml.jackson.databind.ser.impl.SimpleFilterProvider;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -172,10 +173,12 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	 */
 	protected void configureObjectMapper(ObjectMapper mapper) {
 		mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
+		mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
 		mapper.configure(MapperFeature.USE_STD_BEAN_NAMING, true);
 		mapper.setSerializationInclusion(Include.NON_NULL);
 		applyConfigurationPropertiesFilter(mapper);
 		applySerializationModifier(mapper);
+		mapper.registerModule(new JavaTimeModule());
 	}
 
 	private ObjectMapper getObjectMapper() {

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.context.properties;
 
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -157,6 +158,16 @@ public class ConfigurationPropertiesReportEndpointTests {
 		});
 	}
 
+	@Test
+	public void duration() {
+		load((context, properties) -> {
+			Map<String, Object> nestedProperties = properties.getBeans()
+					.get("testProperties").getProperties();
+			assertThat(nestedProperties.get("duration"))
+					.isEqualTo(Duration.ofSeconds(10).toString());
+		});
+	}
+
 	@Test
 	public void singleLetterProperty() {
 		load((context, properties) -> {
@@ -276,6 +287,8 @@ public class ConfigurationPropertiesReportEndpointTests {
 
 		private String nullValue = null;
 
+		private Duration duration = Duration.ofSeconds(10);
+
 		public TestProperties() {
 			this.secrets.put("mine", "myPrivateThing");
 			this.secrets.put("yours", "yourPrivateThing");
@@ -379,6 +392,14 @@ public class ConfigurationPropertiesReportEndpointTests {
 			this.nullValue = nullValue;
 		}
 
+		public Duration getDuration() {
+			return this.duration;
+		}
+
+		public void setDuration(Duration duration) {
+			this.duration = duration;
+		}
+
 		public static class Hidden {
 
 			private String mine = "mySecret";