The Google Pub/Sub connector allows you to access the exposed API through the WSO2 EI. Google Cloud Pub/Sub is a fully-managed real-time messaging service that allows you to send and receive messages between independent applications.
Google Pub/Sub EI connector documentation v1.0.0
mvn clean install
You can create a third party connector and publish in WSO2 Connector Store.
https://docs.wso2.com/display/ESBCONNECTORS/Creating+and+Publishing+a+Third+Party+Connector