diff --git a/src/main/java/org/codelibs/fess/script/ognl/OgnlEngine.java b/src/main/java/org/codelibs/fess/script/ognl/OgnlEngine.java
index 7f77e0c..49e96cc 100644
--- a/src/main/java/org/codelibs/fess/script/ognl/OgnlEngine.java
+++ b/src/main/java/org/codelibs/fess/script/ognl/OgnlEngine.java
@@ -27,9 +27,22 @@
 
 import ognl.Ognl;
 
+/**
+ * Script engine that evaluates OGNL (Object-Graph Navigation Language) expressions.
+ * <p>
+ * The Fess DI container is exposed to the expression context under the {@code container} key,
+ * allowing scripts to access registered components.
+ */
 public class OgnlEngine extends AbstractScriptEngine {
     private static final Logger logger = LogManager.getLogger(OgnlEngine.class);
 
+    /**
+     * Creates a new {@link OgnlEngine}.
+     */
+    public OgnlEngine() {
+        super();
+    }
+
     @Override
     public Object evaluate(final String template, final Map<String, Object> paramMap) {
         if (StringUtil.isBlank(template)) {