How to integrate google docs with my java web application?

I have application in which I have integrated ms office 365 , so user can open docx or xlsx pptx file from my web application to office 365 frame & Multiple users can co-auther it . Now I want to provide similar integration of Google docs , sheets , powerpoint. I got apis from sheets and powerpoint . But I am not getting any idea from searching it on internet. This link contains only apis for spreadsheet and powerpoint but not for docs. https://console.developers.google.com/apis/library