UNOMI-401: correctly set ClassLoader before MVEL script execute (#215)

diff --git a/scripting/src/main/java/org/apache/unomi/scripting/MvelScriptExecutor.java b/scripting/src/main/java/org/apache/unomi/scripting/MvelScriptExecutor.java
index f0fdd51..8777b0f 100644
--- a/scripting/src/main/java/org/apache/unomi/scripting/MvelScriptExecutor.java
+++ b/scripting/src/main/java/org/apache/unomi/scripting/MvelScriptExecutor.java
@@ -44,12 +44,13 @@
 
         final ClassLoader tccl = Thread.currentThread().getContextClassLoader();
         try {
+            Thread.currentThread().setContextClassLoader(secureFilteringClassLoader);
+
             if (!mvelExpressions.containsKey(script)) {
 
                 if (expressionFilterFactory.getExpressionFilter("mvel").filter(script) == null) {
                     mvelExpressions.put(script, INVALID_SCRIPT_MARKER);
                 } else {
-                    Thread.currentThread().setContextClassLoader(secureFilteringClassLoader);
                     ParserConfiguration parserConfiguration = new ParserConfiguration();
                     parserConfiguration.setClassLoader(secureFilteringClassLoader);
                     ParserContext parserContext = new ParserContext(parserConfiguration);