title: jasper reports grouping not working as expected
body: <p>I am running a jasper report on an select query, I am grouping the result by few values and using the same fields in my header
  Below is my jasper group expression and header.</p>
  
  <pre><code>&lt;groupExpression&gt;&lt;![CDATA[$F{tray_code} + $F{card_id} + $F{card_position}+$F{card_number}+ $F{card_from_date}+ $F{card_to_date} + $F{week_number}+$F{patient_id} + $F{patient_full_name}]]&gt;&lt;/groupExpression&gt;
      &lt;groupHeader&gt;
          &lt;band height="15"&gt;
              &lt;textField isBlankWhenNull="true"&gt;
                  &lt;reportElement x="5" y="0" width="20" height="14" uuid="97fd5e2c-50e4-46e4-9c1b-0453f5cd05b5"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{tray_code}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField isBlankWhenNull="true"&gt;
                  &lt;reportElement x="26" y="0" width="44" height="14" uuid="d16ea2fb-367a-4b5e-986e-bc19669c3091"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{card_id}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField&gt;
                  &lt;reportElement x="95" y="0" width="25" height="14" uuid="b7eb1f75-44d4-467e-8463-29f6f6f4555b"/&gt;
                  &lt;textElement textAlignment="Center"&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{card_position}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField pattern=""&gt;
                  &lt;reportElement x="120" y="0" width="55" height="14" uuid="10e4bc1b-cfbb-478d-bd10-a6284bd3bac1"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[new SimpleDateFormat("dd/MM/yyyy").format(new SimpleDateFormat("yyyy-MM-dd").parse($F{card_from_date}))]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField pattern="dd/MM/yyyy"&gt;
                  &lt;reportElement x="175" y="0" width="55" height="14" uuid="a7d34de5-c4de-4093-9da7-96119450c3ab"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[new SimpleDateFormat("dd/MM/yyyy").format(new SimpleDateFormat("yyyy-MM-dd").parse($F{card_to_date}))]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField&gt;
                  &lt;reportElement x="230" y="0" width="24" height="14" uuid="9cf3bce2-cb70-45e7-8199-0d6c8003ce53"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{week_number}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField&gt;
                  &lt;reportElement x="270" y="0" width="67" height="14" uuid="d9e50bb7-1616-4d84-b92f-246abd05ae7b"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{patient_id}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;textField&gt;
                  &lt;reportElement x="337" y="0" width="250" height="14" uuid="b06f0d0d-739b-4e2a-a2bc-1686c9d5cbfe"/&gt;
                  &lt;textElement&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{patient_full_name}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
              &lt;line&gt;
                  &lt;reportElement x="0" y="14" width="752" height="1" uuid="968c2e25-462d-4b0a-90e2-34570db25d0f"/&gt;
                  &lt;graphicElement&gt;
                      &lt;pen lineWidth="1.0" lineStyle="Dashed" lineColor="#999999"/&gt;
                  &lt;/graphicElement&gt;
              &lt;/line&gt;
              &lt;textField&gt;
                  &lt;reportElement x="70" y="0" width="25" height="14" uuid="7f4ba299-706f-4ba6-aafc-ffa47b0e4374"/&gt;
                  &lt;textElement textAlignment="Center"&gt;
                      &lt;font fontName="DejaVu Sans" size="8" isBold="true"/&gt;
                  &lt;/textElement&gt;
                  &lt;textFieldExpression&gt;&lt;![CDATA[$F{card_number}]]&gt;&lt;/textFieldExpression&gt;
              &lt;/textField&gt;
          &lt;/band&gt;
      &lt;/groupHeader&gt;
  </code></pre>
  
  <p>According to the above group expression, I expect only one header for a group, But I see the group header for the same group is repeated in my output file ! Please let me know what I am doing wrong.
  Thanks in Advance.</p>