Bug 135207 parameter dialog is not displayed when drill through to a PDF report that contains parameter with no default value
steps to reproduce: - create 1st report - add a report parameter (no default value) - create 2nd report - add a label "link" - edit hyperlink property (type: drill-through, target report format: PDF) - preview 1st report - click on "link" expected behavior: - parameter dialog should be displayed - target report is rendered in PDF format actual behavior: - "Some required parameter values are not set or set to incompatible data type." was displayed instead.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/servlet/ViewerServlet.java
* <p>
 * Each public mapping expects some URL parameters,
 * <ul>
 * <li>Frameset
 * <ul>
 * <li>__report</li>
 * <li>__locale</li>
 * <li><i>report parameter</i></li>
 * </ul>
 * <li>Run
 * <ul>
 * <li>__report</li>
 * <li>__format</li>
 * <li>__locale</li>
 * <li>__page</li>
 * <li><i>report parameter</i></li>
 * </ul>
 * </ul>
 * <p>
 * Each URL parameter is described below. <table border=1>
 * <tr>
 * <td><b>Parameter</b></td>
 * <td><b>Description</b></td>
 * <td><b>Values</b></td>
 * <td><b>Default</b></td>
 * </tr>
 * <tr>
 * <td>__report</td>
 * <td>The path to the report document</td>
 * <td>&nbsp;</td>