Add thread safe wrapper for Invocable

pom.xml

@@ -41,6 +41,11 @@
             <artifactId>yamlbeans</artifactId>
             <version>1.15</version>
         </dependency>
+        <dependency>
+            <groupId>net.jcip</groupId>
+            <artifactId>jcip-annotations</artifactId>
+            <version>1.0</version>
+        </dependency>
 
         <!-- Logging -->
         <dependency>

src/main/java/scripting/SynchronizedInvocable.java

@@ -0,0 +1,39 @@
+package scripting;
+
+import net.jcip.annotations.ThreadSafe;
+
+import javax.script.Invocable;
+import javax.script.ScriptException;
+
+/**
+ * Thread safe wrapper around Invocable.
+ * Thread safety is achieved by synchronizing all methods.
+ */
+@ThreadSafe
+public class SynchronizedInvocable implements Invocable {
+    private final Invocable invocable;
+
+    public SynchronizedInvocable(Invocable invocable) {
+        this.invocable = invocable;
+    }
+
+    @Override
+    public synchronized Object invokeMethod(Object thiz, String name, Object... args) throws ScriptException, NoSuchMethodException {
+        return invocable.invokeMethod(thiz, name, args);
+    }
+
+    @Override
+    public synchronized Object invokeFunction(String name, Object... args) throws ScriptException, NoSuchMethodException {
+        return invocable.invokeFunction(name, args);
+    }
+
+    @Override
+    public synchronized <T> T getInterface(Class<T> clasz) {
+        return invocable.getInterface(clasz);
+    }
+
+    @Override
+    public synchronized <T> T getInterface(Object thiz, Class<T> clasz) {
+        return invocable.getInterface(thiz, clasz);
+    }
+}