FAQ.md

@@ -145,6 +145,23 @@ Visit https://github.com/openapitools/openapi-generator and then click on the "F
 6) git push origin fix_issue9999
 7) Visit https://github.com/openapitools/openapi-generator in your browser and click on the button to file a new PR based on fix_issue9999
 
+### How can I submit a PR for a branch (e.g. 4.2.x)?
+
+Visit https://github.com/openapitools/openapi-generator and then click on the "Fork" button in the upper right corner. Then in your local machine, run the following (assuming your github ID is "your_user_id")
+
+1) git clone https://github.com/your_user_id/openapi-generator.git
+2) cd openapi-generator
+3) git remote add upstream https://github.com/openapitools/openapi-generator
+3) git checkout 4.2.x
+4) git pull usptream 4.2.x (ensure it has the latest change)
+5) git log (review the latest change to this branch)
+6) git checkout -b 4.2.x-enhance (create a new branch instead of modifying 4.2.x directly)
+7) make changes
+8) git commit -a (you may need to use `git add filename` to add new files)
+9) git push origin 4.2.x-enhance
+10) Visit https://github.com/openapitools/openapi-generator in your browser and click on the button to file a new PR based on 4.2.x-enhance. Make sure the PR is filed against "4.2.x" branch instead of master.
+11) After the branch is merged, repeat step 3 & 4
+
 ## Java
 
 ### Using Java API client to make request results in SSL errors due to an invalid certificate. Is there a way to bypass that?