// Add budget.
BudgetOperation budgetOperation = new BudgetOperation();
budgetOperation.setOperand(budget);
budgetOperation.setOperator(Operator.ADD);
BudgetReturnValue budgetReturnValue =
budgetService.mutate(new BudgetOperation[] {budgetOperation});
// Set the budget to the campaign.
Budget createdBudget = new Budget();
createdBudget.setBudgetId(budgetReturnValue.getValue(0).getBudgetId());
campaign.setBudget(createdBudget);