Fix #4309 (#4320)

Author: JooHyukKim

release-notes/VERSION-2.x

@@ -31,6 +31,10 @@ Project: jackson-databind
 #4262: Improve handling of `null` insertion failure for `TreeSet`
 #4263: Change `ObjectArrayDeserializer` to use "generic" type parameter
   (`java.lang.Object`) to remove co-variant return type
+#4309: `@JsonSetter(nulls=...)` handling of `Collection` `null` values during
+  deserialization with `READ_UNKNOWN_ENUM_VALUES_AS_NULL` and `FAIL_ON_INVALID_SUBTYPE` wrong
+ (reported by @ivan-zaitsev)
+ (fix contributed by Joo-Hyuk K)
 
 2.16.2 (not yet released)
 

src/main/java/com/fasterxml/jackson/databind/deser/std/CollectionDeserializer.java

@@ -413,15 +413,15 @@ protected final Collection<Object> handleNonArray(JsonParser p, DeserializationC
                     return result;
                 }
                 value = _nullProvider.getNullValue(ctxt);
-                if (value == null) {
-                    _tryToAddNull(p, ctxt, result);
-                    return result;
-                }
             } else if (typeDeser == null) {
                 value = valueDes.deserialize(p, ctxt);
             } else {
                 value = valueDes.deserializeWithType(p, ctxt, typeDeser);
             }
+            if (value == null) {
+                _tryToAddNull(p, ctxt, result);
+                return result;
+            }
         } catch (Exception e) {
             boolean wrap = ctxt.isEnabled(DeserializationFeature.WRAP_EXCEPTIONS);
             if (!wrap) {
@@ -464,6 +464,9 @@ protected Collection<Object> _deserializeWithObjectId(JsonParser p, Deserializat
                 } else {
                     value = valueDes.deserializeWithType(p, ctxt, typeDeser);
                 }
+                if (value == null && _skipNullValues) {
+                    continue;
+                }
                 referringAccumulator.add(value);
             } catch (UnresolvedForwardReference reference) {
                 Referring ref = referringAccumulator.handleUnresolvedReference(reference);
@@ -480,14 +483,18 @@ protected Collection<Object> _deserializeWithObjectId(JsonParser p, Deserializat
     }
 
     /**
-     * {@code java.util.TreeSet} does not allow addition of {@code null} values,
-     * so isolate handling here.
+     * {@code java.util.TreeSet} (and possibly other {@link Collection} types) does not
+     * allow addition of {@code null} values, so isolate handling here.
      *
      * @since 2.17
      */
     protected void _tryToAddNull(JsonParser p, DeserializationContext ctxt, Collection<?> set)
         throws IOException
     {
+        if (_skipNullValues) {
+            return;
+        }
+
         // Ideally we'd have better idea of where nulls are accepted, but first
         // let's just produce something better than NPE:
         try {

src/test/java/com/fasterxml/jackson/failing/NullsSkip4309Test.java src/test/java/com/fasterxml/jackson/databind/deser/NullsSkip4309Test.java

@@ -1,13 +1,13 @@
-package com.fasterxml.jackson.failing;
+package com.fasterxml.jackson.databind.deser;
 
 import java.util.List;
 
+import org.junit.jupiter.api.Test;
+
 import com.fasterxml.jackson.annotation.JsonSetter;
 import com.fasterxml.jackson.annotation.JsonSubTypes;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
 import com.fasterxml.jackson.annotation.Nulls;
-import org.junit.jupiter.api.Test;
-
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.json.JsonMapper;