Fix #4552: change MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS default to false (#4555)

Author: cowtowncoder

release-notes/VERSION

@@ -57,6 +57,7 @@ Versions: 3.x (for earlier see VERSION-2.x)
 #3601: Change `Optional` deserialization from "absent" value into `null`, from "empty"
 #4160: Deprecate `DefaultTyping.EVERYTHING` in `2.x` and remove in `3.0`
 #4381: Prevent construction of `null`-valued `JsonNode`s (like `TextNode`)
+#4552: Change `MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS` default to `false` for 3.0
 - Remove `MappingJsonFactory`
 - Add context parameter for `TypeSerializer` contextualization (`forProperty()`)
 - Default for `JsonNodeFeature.STRIP_TRAILING_BIGDECIMAL_ZEROES` changed to `false` for 3.0

src/main/java/tools/jackson/databind/MapperFeature.java

@@ -78,9 +78,9 @@ public enum MapperFeature
      * rules; if disabled, such fields are NOT used as mutators except if
      * explicitly annotated for such use.
      *<p>
-     * Feature is enabled by default, for backwards compatibility reasons.
+     * Feature is disabled by default in Jackson 3.x, in 2.x it was enabled by default.
      */
-    ALLOW_FINAL_FIELDS_AS_MUTATORS(true),
+    ALLOW_FINAL_FIELDS_AS_MUTATORS(false),
 
     /**
      * Feature that determines whether member mutators (fields and

src/test/java/tools/jackson/databind/objectid/ObjectId3838Test.java

@@ -37,7 +37,8 @@ public String result() {
 
     @JsonIdentityInfo(property = "id", generator = ObjectIdGenerators.PropertyGenerator.class)
     static class CreatorBased implements ResultGetter {
-        private final String id;
+        // NOTE: must NOT be `final` unless `MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS` enabled
+        private String id;
 
         @JsonCreator
         CreatorBased(@JsonProperty(value = "id") String id) {
@@ -66,7 +67,8 @@ public String result() {
 
     @JsonIdentityInfo(property = "id", generator = ObjectIdGenerators.PropertyGenerator.class)
     static class StaticFactoryMethodBased implements ResultGetter {
-        private final String id;
+        // NOTE: must NOT be `final` unless `MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS` enabled
+        private String id;
 
         private StaticFactoryMethodBased(String id) {
             this.id = id;
@@ -89,7 +91,9 @@ public String result() {
 
     @JsonIdentityInfo(property = "id", generator = ObjectIdGenerators.PropertyGenerator.class)
     static class MultiArgConstructorBased implements ResultGetter {
-        private final String id;
+        // NOTE: must NOT be `final` unless `MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS` enabled
+        private String id;
+
         private final int value;
 
         @JsonCreator