Workflow workflow = this.engine.getWorkflow();
JythonScript script = new JythonScript(workflow, this.engine.getConfiguration());
// Check if there is any errors in the workflow first.
ArrayList<String> warnings = new ArrayList<String>();
if (!script.validate(warnings)) {
StringBuilder buf = new StringBuilder();
for (String warning : warnings) {
buf.append("- ");
buf.append(warning);
buf.append("\n");