composite and mixed supply (sec 8) 🙅🏾‍♂️

In case of a composite supply, rate of GSt is charged as amounts to the principal component or predominant supply and
in case of.mixed supply rate shall be the highest of the supplies.
in case tax invoice issue rate of GSt shall be charged on the amount of composite or mixed supply!
but what in case a person buys alcohol and aerated water to have together ?
composite or mixed supply or separately shown in invoice?😂
I know this may be a dumb question, who cares whatsoever!