1- In bot definition, replace <AWS_ACCOUNT_ID> with your account id.
2- Import the definition using Lex V1 console.
3- Grant Lex permisison to invoke Lambda
aws lambda add-permission --function-name waf_validation --statement-id chatbot-fulfillment1 --action "lambda:InvokeFunction" --principal "lex.amazonaws.com" --region us-west-2
aws lambda add-permission --function-name waf_fulfilment --statement-id chatbot-fulfillment2 --action "lambda:InvokeFunction" --principal "lex.amazonaws.com" --region us-west-2
4-Change handler name in Lambda configuration.
6-Follow Step2 to Step6 given at https://docs.aws.amazon.com/lex/latest/dg/slack-bot-association.html to create a Slack application that integrates with our Lex bot.