How to get the r-squared of the testing data from an H2O-generated model in rstudio?

How to get the r-squared of the testing data from an H2O-generated model in rstudio?
I know how to get other metrics using the function?
h2o.performance(model, xval = TRUE, newdata = testing)

However, I need to know the method to return the r-squared for testing data

Hello guys can you help please?