@Override
    public Object execute(ComplexEvent event) {
        Object leftObject = leftExpressionExecutor.execute(event);
        Object rightObject = rightExpressionExecutor.execute(event);
        if (leftObject == null || rightObject == null) {
            return null;
        }
        return ((Number) leftObject).longValue() * ((Number) rightObject).longValue();
    }
Executor class for Long Multiply function. Function execution logic is implemented in execute here.
modules/siddhi-core/src/main/java/io/siddhi/core/executor/math/multiply/MultiplyExpressionExecutorLong.java