Bug 214204 Only document content in document folder should be removed.[0601]
Description: Only document related content in document folder should be removed. Build number:2.3.0.v20080103 Steps to reproduce: 1. Deploy BIRT. 2. Edit web.xml to set BIRT_VIEWER_DOCUMENT_FOLDER to your local path and there are content inside the path. 3. Start server and click View Example to preview sample report. Expected result: Only content created by viewer should be removed in specified document folder. Actual result: All contents are deleted despite whether they are related with BIRT. Error log:n/a
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
* URL parameter name to indicate whether clean session files.
	 */
	public static final String PARAM_CLEAN_SESSION = "__clean"; 
	/**
	 * URL parameter name to indicate if force optimized HTML output.
	 */
	public static final String PARAM_AGENTSTYLE_ENGINE = "__agentstyle"; 
	/**
	 * Custom request headers to identify the request is a normal HTTP request
	 * or a soap request by AJAX.
	 */
	public static final String HEADER_REQUEST_TYPE = "request-type"; 
	/**
	 * The request type of "soap".
	 */
	public static final String HEADER_REQUEST_TYPE_SOAP = "soap"; 
	/**
	 * Parameter name that gives the IID of the export data form.
	 */
	public static final String PARAM_IID = "iid"; 
	/**
	 * Parameter name that gives the result set names of the export data form.
	 */
	public static final String PARAM_RESULTSETNAME = "ResultSetName"; 
	/**
	 * Parameter name that gives the selected column numbers of the export data
	 * form.
	 */
	public static final String PARAM_SELECTEDCOLUMNNUMBER = "SelectedColumnNumber"; 
	/**