Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/ir/Report.java
}
	public Set getStyleSet( )
	{
		return styleTable.entrySet( );
	}
	/**
	 * Finds the style in the report.
	 * 
	 * @param name
	 *            The name of the style.
	 * @return The corresponding <code>StyleDesign</code> object.
	 */
	public IStyle findStyle( String name )
	{
		if ( name == null )
		{
			return null;
		}
		return (IStyle) this.styleTable.get( name );
	}
	/**
	 * Appends a top-level parameter or parameter group in the report.
	 * 
	 * @param parameter
	 *            The parameter or parameter group object.
	 */
	public void addParameter( IParameterDefnBase parameter )
	{
		assert ( parameter != null );
		assert ( parameter.getName( ) != null );