React Apollo updateResponse Question

updateResponse.js

updateUser: (variables) => {
  return mutate({
    variables,
    
    // when using optimisticResponse and I don't include the values, I get a warning.
    optimisticResponse: {
      updateUser: {
        __typename: 'User',
        id: 'xyz',
        setting: undefined,
        setting2: true
      }
    },
    
    update: (store, { data: { updateUser } }) => {
    }
  })
  
})

variables.js

// ANY one of these can be optional
{
  setting, 
  setting2,
  setting3
}