The norm for hosting custom cordova plugins is one plugin per git repository. However there are instances when you would want to host multiple custom plugins inside the same repository. The cordova command for adding such plugins into a cordova project is as given below :
cordova plugin add [GIT_REPO_URL]#[BRANCH_NAME]:[FOLDER_PATH]
cordova plugins add https://firstname.lastname@example.org/harinis/gtnexuscordovaplugins.git#master:attachmentHandler
Note that the FOLDER_PATH should point to the main plugin folder that contains the plugin.xml file.