Remove duplicated default in manual Jackson metadata

Closes gh-49797

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfiguration.java

@@ -326,19 +326,15 @@ public class JacksonAutoConfiguration {
 
 			private void configureConstructorDetector(Jackson2ObjectMapperBuilder builder) {
 				ConstructorDetectorStrategy strategy = this.jacksonProperties.getConstructorDetector();
-				if (strategy != null) {
-					builder.postConfigurer((objectMapper) -> {
-						switch (strategy) {
-							case USE_PROPERTIES_BASED ->
-								objectMapper.setConstructorDetector(ConstructorDetector.USE_PROPERTIES_BASED);
-							case USE_DELEGATING ->
-								objectMapper.setConstructorDetector(ConstructorDetector.USE_DELEGATING);
-							case EXPLICIT_ONLY ->
-								objectMapper.setConstructorDetector(ConstructorDetector.EXPLICIT_ONLY);
-							default -> objectMapper.setConstructorDetector(ConstructorDetector.DEFAULT);
-						}
-					});
-				}
+				builder.postConfigurer((objectMapper) -> {
+					switch (strategy) {
+						case USE_PROPERTIES_BASED ->
+							objectMapper.setConstructorDetector(ConstructorDetector.USE_PROPERTIES_BASED);
+						case USE_DELEGATING -> objectMapper.setConstructorDetector(ConstructorDetector.USE_DELEGATING);
+						case EXPLICIT_ONLY -> objectMapper.setConstructorDetector(ConstructorDetector.EXPLICIT_ONLY);
+						default -> objectMapper.setConstructorDetector(ConstructorDetector.DEFAULT);
+					}
+				});
 			}
 
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/JacksonProperties.java

@@ -104,7 +104,7 @@ public class JacksonProperties {
 	 * Strategy to use to auto-detect constructor, and in particular behavior with
 	 * single-argument constructors.
 	 */
-	private ConstructorDetectorStrategy constructorDetector;
+	private ConstructorDetectorStrategy constructorDetector = ConstructorDetectorStrategy.DEFAULT;
 
 	/**
 	 * Time zone used when formatting dates. For instance, "America/Los_Angeles" or

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -1854,10 +1854,6 @@
       "name": "spring.info.git.location",
       "defaultValue": "classpath:git.properties"
     },
-    {
-      "name": "spring.jackson.constructor-detector",
-      "defaultValue": "default"
-    },
     {
       "name": "spring.jackson.datatype.enum",
       "description": "Jackson on/off features for enums."