warmUp
Performs a warm-up for the SDK. Safe to call and start a transaction without waiting for the result.
This will:
Establish a new session if necessary.
Fetch configuration if necessary.
As a best practice, call the warm-up function:
When the POS app starts. In other words, as soon as the app has the active state.
When the POS app returns to the active state after running in the background.
Return
a successful Result if warm up was able to be completed, or a failure with one of the following exceptions:
TransactionInProgressException if warm up is called and a transaction is in progress
WarmUpInProgressException if warm up is called and a warm up is in progress
WarmUpFailedException if warm up started but failed to execute