fix ReflectionUtils traversal issue that was failing for some Java types e.g. java.time.LocalDate

Author: MoonWorm

examples/pom.xml

@@ -19,7 +19,7 @@
     </modules>
 
     <properties>
-        <jsonapi4j.version>1.8.3-SNAPSHOT</jsonapi4j.version>
+        <jsonapi4j.version>1.8.3</jsonapi4j.version>
 
         <jakarta.servlet-api.version>6.1.0</jakarta.servlet-api.version>
 

jsonapi4j-base/src/main/java/pro/api4/jsonapi4j/util/ReflectionUtils.java

@@ -241,7 +241,6 @@ private static void traverse(Class<?> clazz,
         }
         visited.add(clazz);
         for (Field field : clazz.getDeclaredFields()) {
-            field.setAccessible(true);
             String path = prefix.isEmpty()
                     ? field.getName()
                     : prefix + "." + field.getName();
@@ -260,7 +259,31 @@ private static boolean isLeafType(Class<?> clazz) {
                 || Boolean.class.equals(clazz)
                 || Character.class.equals(clazz)
                 || Date.class.isAssignableFrom(clazz)
-                || clazz.isEnum();
+                || clazz.isEnum()
+                || isJdkType(clazz);
+    }
+
+    /**
+     * Treats platform (JDK) types as opaque leaves so traversal never descends into them. JDK value
+     * types such as {@code java.time.LocalDate}, {@code java.util.UUID} or {@code java.math.BigDecimal}
+     * carry no domain-meaningful field paths, and the module system forbids making their internal
+     * fields accessible (e.g. {@code java.base} does not open {@code java.time} to the unnamed module).
+     */
+    private static boolean isJdkType(Class<?> clazz) {
+        if (clazz.isArray()) {
+            return false;
+        }
+        Package pkg = clazz.getPackage();
+        if (pkg == null) {
+            return false;
+        }
+        String name = pkg.getName();
+        return name.startsWith("java.")
+                || name.startsWith("javax.")
+                || name.startsWith("jakarta.")
+                || name.startsWith("sun.")
+                || name.startsWith("com.sun.")
+                || name.startsWith("jdk.");
     }
 
     /**

jsonapi4j-base/src/test/java/pro/api4/jsonapi4j/plugin/utils/ReflectionUtilsTests.java

@@ -43,6 +43,24 @@ public void getAllFieldPaths_happyPath_checkResult() {
         );
     }
 
+    @Test
+    public void getAllFieldPaths_jdkValueTypeAttributes_treatedAsLeavesAndNotTraversed() {
+        // given - when
+        Set<String> paths = ReflectionUtils.getAllFieldPaths(JdkTypes.class);
+
+        // then - JDK value types are leaf paths; traversal must not descend into their internals
+        // (descending into e.g. java.time.LocalDate would throw InaccessibleObjectException)
+        assertThat(paths).isEqualTo(
+                Set.of(
+                        "localDate",
+                        "localDateTime",
+                        "instant",
+                        "uuid",
+                        "amount"
+                )
+        );
+    }
+
     @Test
     public void setFieldPathValueThrowing_nullObject_checkResult() {
         // given
@@ -226,6 +244,14 @@ public class Nested {
         Nested nested;
     }
 
+    public class JdkTypes {
+        java.time.LocalDate localDate;
+        java.time.LocalDateTime localDateTime;
+        java.time.Instant instant;
+        java.util.UUID uuid;
+        java.math.BigDecimal amount;
+    }
+
     public class PathsTraversal {
         A a;
         String s;

pom.xml

@@ -52,7 +52,7 @@
 
     <properties>
         <!--project revision-->
-        <revision>1.8.3-SNAPSHOT</revision>
+        <revision>1.8.3</revision>
 
         <!--spting/web-->
         <spring.version>5.3.14</spring.version>