Improve comment for ObjectMissingException throw

Copilot · sbrunner · Copilot · commit 88ca4c940786 · 2026-02-11T14:12:04.000Z
Add detailed comment explaining why ObjectMissingException is thrown for
empty default values, clarifying the rationale for the framework.

Co-authored-by: sbrunner &lt;353872+sbrunner@users.noreply.github.com&gt;
diff --git a/core/src/main/java/org/mapfish/print/attribute/ReflectiveAttribute.java b/core/src/main/java/org/mapfish/print/attribute/ReflectiveAttribute.java
@@ -441,8 +441,12 @@ public Object getValue(
         throw new IllegalArgumentException(message);
       }
       pValue = this.getDefaultValue();
-      // If the attribute is missing from the request and has no meaningful default,
-      // throw ObjectMissingException to let the framework handle it properly
+      // If the attribute is missing from the request and has no meaningful default
+      // (i.e., the default value is an empty object), throw ObjectMissingException.
+      // This prevents attempting to parse an empty object which would trigger
+      // OneOf validation errors for required fields. The framework will handle this
+      // by either throwing MissingPropertyException for required attributes or
+      // skipping optional attributes.
       if (pValue != null && !pValue.keys().hasNext()) {
         throw new ObjectMissingException(
             requestJsonAttributes, attributeName);
