How to add new methods from the WebDriver Spec

First, check here for the supported HTTP endpoints:

https://github.com/SeleniumHQ/selenium/blob/master/java/client/src/org/openqa/selenium/remote/http/JsonHttpCommandCodec.java

Find the action there you want to implement, and add an entry to the mapping in Selenium::Remote::Commands

Next, figure out the "canonical" name to have the verb be:

https://github.com/SeleniumHQ/selenium/blob/master/java/client/src/org/openqa/selenium/remote/DriverCommand.java

Set that as the name of the action you just created in Selenium::Remote::Commands.

When implementing the method in Selenium::Remote::Driver, if you aren't particularly sure of what kind of arguments it takes, consult these pages:

• https://github.com/SeleniumHQ/selenium/blob/master/java/server/src/org/openqa/selenium/remote/server/JsonHttpCommandHandler.java - this one will show you what classes correspond to what verb
• https://seleniumhq.github.io/selenium/docs/api/java/org/openqa/selenium/remote/server/handler/WebDriverHandler.html - this one will show you the classes themselves (and ergo their actual argument structure).
• https://github.com/SeleniumHQ/selenium/tree/master/java/server/src/org/openqa/selenium/remote/server/handler - can also be helpful if it's got a special component to the URI that's needed

Otherwise, just "ape your betters" in general and copy/paste a similar method and alter the relevant bits.