if (processor == null) {
                throw new ExprValidationException("A named window by name '" + onTriggerDesc.getWindowName() + "' does not exist");
            }
            // validate context
            processor.validateOnExpressionContext(contextName);
            EventType namedWindowType = processor.getNamedWindowType();
            outputEventType = namedWindowType;
            services.getStatementEventTypeRefService().addReferences(statementContext.getStatementName(), new String[] {onTriggerDesc.getWindowName()});