Add support for java.util.Optional to the empty operator.

Author: markt-asf

java/org/apache/el/parser/AstAbstractEmpty.java

@@ -19,6 +19,7 @@
 
 import java.util.Collection;
 import java.util.Map;
+import java.util.Optional;
 
 import jakarta.el.ELException;
 
@@ -52,7 +53,8 @@ public Object getValue(EvaluationContext ctx) throws ELException {
         if (obj == null || obj instanceof String && ((String) obj).isEmpty() ||
                 obj instanceof Object[] && ((Object[]) obj).length == 0 ||
                 obj instanceof Collection<?> && ((Collection<?>) obj).isEmpty() ||
-                obj instanceof Map<?,?> && ((Map<?,?>) obj).isEmpty()) {
+                obj instanceof Map<?,?> && ((Map<?,?>) obj).isEmpty() ||
+                obj instanceof Optional && ((Optional<?>) obj).isEmpty()) {
             return RETURN_EMPTY;
         }
         return RETURN_NOT_EMPTY;

webapps/docs/changelog.xml

@@ -355,6 +355,10 @@
         Add support for coercion to <code>java.time.Instant</code> and
         <code>java.util.Date</code>. (markt)
       </add>
+      <add>
+        Add support for <code>java.util.Optional</code> to the empty operator.
+        (markt)
+      </add>
       <!-- Entries for backport and removal before 12.0.0-M1 below this line -->
       <fix>
         <bug>69948</bug>: Avoid ArrayOutOfBoundsException instead of