add validation funcion

Author: lxning

frontend/server/src/main/java/org/pytorch/serve/wlm/ModelManager.java

@@ -239,10 +239,7 @@ private void setupModelDependencies(Model model)
                             null);
 
             ProcessBuilder processBuilder = new ProcessBuilder(commandParts);
-            if (dependencyPath
-                    .toPath()
-                    .normalize()
-                    .startsWith(FileUtils.getTempDirectory().toPath().normalize())) {
+            if (isValidDependencyPath(dependencyPath)) {
                 processBuilder.directory(dependencyPath);
             } else {
                 throw new ModelException(
@@ -285,6 +282,16 @@ private void setupModelDependencies(Model model)
         }
     }
 
+    private boolean isValidDependencyPath(File dependencyPath) {
+        if (dependencyPath
+                .toPath()
+                .normalize()
+                .startsWith(FileUtils.getTempDirectory().toPath().normalize())) {
+            return true;
+        }
+        return false;
+    }
+
     private Model createModel(
             ModelArchive archive,
             int batchSize,