Java - please implement "toString()" method of your "ApiGatewayResponse" object?

generated an aws java maven project and trying to run lambda locally…

Serverless: In order to get human-readable output, please implement "toString()" method of your "ApiGatewayResponse" object.
no main manifest attribute, in /Users/newadmin/.nvm/versions/node/v8.9.4/lib/node_modules/serverless/lib/plugins/aws/invokeLocal/java/target/invoke-bridge-1.0.jar