Bug 183919 [Enhancement] add a switch to determine whether to clean viewer image folder when session expires
in current viewer implementation, file in image folder is deleted when its corresponding session expires, could viewer add a switch to allow users to decide whether this deletion operation should be performed.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
}
		return value;
	}
	/**
	 * Get result set name.
	 * 
	 * @param request
	 * @return
	 */
	public static String getResultSetName( HttpServletRequest request )
	{
		return getReportParameter( request, PARAM_RESULTSETNAME, null );
	}
	/**
	 * Get solected column name list.
	 * 
	 * @param request
	 * @return
	 */
	public static Collection getSelectedColumns( HttpServletRequest request )
	{
		ArrayList columns = new ArrayList( );
		int columnCount = getParameterAsInt( request,
				PARAM_SELECTEDCOLUMNNUMBER );
		for ( int i = 0; i < columnCount; i++ )
		{
			String paramName = PARAM_SELECTEDCOLUMN + String.valueOf( i );
			String columnName = getParameter( request, paramName );
			columns.add( columnName );
		}