How to hide page header band on last page - variables

Question

I think I am having a problem with evaluation time. In this example, you see the variable $P{REPORT_PARAMETERS_MAP}.get("LastPageNumber") reflecting the last page correctly; it updates correctly. But when I use it for the "printWhenExpression" of a detail band field (experiment) or for the page header band (my goal) it does not work.
I am using "page" evaluation time throughout which seems to work for the variable itself. But the printWhenExpressions are not working using this variable.
Here is my xml file :
<?xml version="1.0" encoding="UTF-8"?>
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="report3" language="groovy" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
<queryString>
<![CDATA[select * from users]]>
</queryString>
<field name="userName" class="java.lang.String">
<fieldDescription><![CDATA[]]></fieldDescription>
</field>
<pageHeader>
<band height="23" splitType="Stretch">
<textField evaluationTime="Page">
<reportElement x="120" y="0" width="238" height="20">
<printWhenExpression><![CDATA[!$V{PAGE_NUMBER}.equals($P{REPORT_PARAMETERS_MAP}
.get("LastPageNumber"))]]></printWhenExpression>
</reportElement>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA["please don't print on last page - page header"]]></textFieldExpression>
</textField>
<textField evaluationTime="Page">
<reportElement x="380" y="0" width="175" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA["last page variable is: " + $V{PAGE_NUMBER}.equals($P{REPORT_PARAMETERS_MAP}
.get("LastPageNumber"))]]></textFieldExpression>
</textField>
<textField>
<reportElement x="2" y="2" width="100" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA["Page header"]]></textFieldExpression>
</textField>
</band>
</pageHeader>
<detail>
<band height="21" splitType="Stretch">
<textField evaluationTime="Page">
<reportElement x="381" y="0" width="174" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA["last page variable is: " + $V{PAGE_NUMBER}.equals($P{REPORT_PARAMETERS_MAP}
.get("LastPageNumber"))]]></textFieldExpression>
</textField>
<textField>
<reportElement x="0" y="0" width="100" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA[$F{userName}]]></textFieldExpression>
</textField>
<textField evaluationTime="Page">
<reportElement x="119" y="0" width="191" height="20">
<printWhenExpression><![CDATA[!$V{PAGE_NUMBER}.equals($P{REPORT_PARAMETERS_MAP}
.get("LastPageNumber"))]]></printWhenExpression>
</reportElement>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA["please don't print on last page - detail"]]></textFieldExpression>
</textField>
</band>
</detail>
<lastPageFooter>
<band height="50">
<line>
<reportElement x="188" y="21" width="100" height="1">
<printWhenExpression><![CDATA[new Boolean($P{REPORT_PARAMETERS_MAP}.put("LastPageNumber",
$V{PAGE_NUMBER}))]]></printWhenExpression>
</reportElement>
</line>
<textField evaluationTime="Page">
<reportElement x="380" y="2" width="174" height="20"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA["last page variable is: " + $V{PAGE_NUMBER}.equals($P{REPORT_PARAMETERS_MAP}
.get("LastPageNumber"))]]></textFieldExpression>
</textField>
</band>
</lastPageFooter>
</jasperReport>
My solution was to make two reports (one for the last page) and then join them (jasperPrints) using the array list option for he jasper exporter:
List jasperPrintList = new ArrayList();
JasperPrint jasperPrint1 =
JasperFillManager.fillReport(
jasperReport1,
parameters,
c
);
JasperPrint jasperPrint2 =
JasperFillManager.fillReport(
jasperReport2,
parameters,
c
);
jasperPrintList.add(jasperPrint1);
jasperPrintList.add(jasperPrint2);
JRPdfExporter exporter = new JRPdfExporter();
ByteArrayOutputStream byte_report = new ByteArrayOutputStream();
exporter.setParameter(JRExporterParameter.JASPER_PRINT_LIST, jasperPrintList);
exporter.setParameter(JRExporterParameter.OUTPUT_FILE_NAME, "test_report_name");
exporter.setParameter(JRExporterParameter.OUTPUT_STREAM, byte_report);
exporter.exportReport();