How to set print when expression for a text in sub report based on the page number of main report

Question

I have a main report which contains sub report in footer. I need to hide a text in the sub report on all pages except the first page. I tried to set print when expression using the following expression:

new AbstractSimpleExpression<Boolean> {

    @Override
    public Boolean evaluate(ReportParameters reportParameters) {
        return reportParameters.getPageNumber() == 1;
    }    
}

But it didn't work. I debugged it and found that reportParameters.getPageNumber() always returns one which I assume to be the page number of sub report. I checked the available methods in reportParameters object and I couldn't found any method to get the page number of main report. Is there any other way to set print when expression for a text in sub report based on the main report's page number?