Fixed hasRequiredMarker to only process content defined in Kotlin

release-notes/CREDITS-2.x

@@ -18,6 +18,7 @@ Contributors:
 # 2.18.4 (not yet released)
 
 WrongWrong (@k163377)
+* #923: Fixed hasRequiredMarker to only process content defined in Kotlin
 * #920: Minor refactors that do not affect behavior
 
 # 2.18.3 (28-Feb-2025)

release-notes/VERSION-2.x

@@ -18,6 +18,8 @@ Co-maintainers:
 
 2.18.4 (not yet released)
 
+#923: Fixed a problem where the result of processing `hasRequiredMarker ` by a `KotlinModule` would also apply to
+  classes defined in `Java` when `NullToEmptyCollection` or `NullToEmptyMap` was enabled.
 #920: Minor refactorings were made that did not affect behavior.
 
 2.18.3 (28-Feb-2025)

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinAnnotationIntrospector.kt

@@ -36,8 +36,10 @@ internal class KotlinAnnotationIntrospector(
     // TODO: implement nullIsSameAsDefault flag, which represents when TRUE that if something has a default value, it can be passed a null to default it
     //       this likely impacts this class to be accurate about what COULD be considered required
 
-    override fun hasRequiredMarker(m: AnnotatedMember): Boolean? {
-        val hasRequired = cache.javaMemberIsRequired(m) {
+    override fun hasRequiredMarker(
+        m: AnnotatedMember
+    ): Boolean? = m.takeIf { it.member.declaringClass.isKotlinClass() }?.let { _ ->
+        cache.javaMemberIsRequired(m) {
             try {
                 when {
                     nullToEmptyCollection && m.type.isCollectionLikeType -> false
@@ -54,7 +56,6 @@ internal class KotlinAnnotationIntrospector(
                 null
             }
         }
-        return hasRequired
     }
 
     override fun findSerializationConverter(a: Annotated): Converter<*, *>? = when (a) {

src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/github/GitHub922.kt

@@ -0,0 +1,32 @@
+package com.fasterxml.jackson.module.kotlin.test.github
+
+import com.fasterxml.jackson.databind.BeanDescription
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.module.kotlin.KotlinFeature
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import kotlin.test.Test
+import kotlin.test.assertTrue
+
+class GitHub922 {
+    private inline fun <reified T : Any> ObjectMapper.introspectSerialization(): BeanDescription =
+        serializationConfig.introspect(serializationConfig.constructType(T::class.java))
+
+    private inline fun <reified T : Any> ObjectMapper.introspectDeserialization(): BeanDescription =
+        deserializationConfig.introspect(deserializationConfig.constructType(T::class.java))
+
+    private fun BeanDescription.isRequired(propertyName: String): Boolean =
+        this.findProperties().first { it.name == propertyName }.isRequired
+
+    @Test
+    fun `nullToEmpty does not override specification by Java annotation`() {
+        val mapper = jacksonObjectMapper {
+            enable(KotlinFeature.NullToEmptyCollection)
+            enable(KotlinFeature.NullToEmptyMap)
+        }
+
+        val desc = mapper.introspectDeserialization<GitHub922RequiredCollectionsDtoJava>()
+
+        assertTrue(desc.isRequired("list"))
+        assertTrue(desc.isRequired("map"))
+    }
+}

src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/github/GitHub922RequiredCollectionsDtoJava.java

@@ -0,0 +1,29 @@
+package com.fasterxml.jackson.module.kotlin.test.github;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.util.List;
+import java.util.Map;
+
+public class GitHub922RequiredCollectionsDtoJava {
+    private final List<String> list;
+    private final Map<String, String> map;
+
+    @JsonCreator
+    public GitHub922RequiredCollectionsDtoJava(
+            @JsonProperty(value = "list", required = true) List<String> list,
+            @JsonProperty(value = "map", required = true) Map<String, String> map
+    ) {
+        this.list = list;
+        this.map = map;
+    }
+
+    public List<String> getList() {
+        return list;
+    }
+
+    public Map<String, String> getMap() {
+        return map;
+    }
+}