Bug 145991 [Regression]Invalid data set should not be allowed to drag or "Insert in layout"
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DataSetHandle.java
* @see org.eclipse.birt.report.model.api.elements.structures.DataSetParameter
	 */
	public Iterator parametersIterator( )
	{
		PropertyHandle propHandle = getPropertyHandle( SimpleDataSet.PARAMETERS_PROP );
		assert propHandle != null;
		return propHandle.iterator( );
	}
	/**
	 * Returns an iterator over the list of parameter bindings. The iterator
	 * returns instances of <code>ParamBindingHandle</code> that represents
	 * parameter binding object.
	 * 
	 * @return iterator over parameter binding.
	 * 
	 * @see org.eclipse.birt.report.model.api.elements.structures.ParamBinding
	 */
	public Iterator paramBindingsIterator( )
	{
		PropertyHandle propHandle = getPropertyHandle( SimpleDataSet.PARAM_BINDINGS_PROP );
		assert propHandle != null;
		return propHandle.iterator( );
	}
	/**
	 * Returns an iterator over the result set columns. The iterator returns
	 * instances of <code>ResultSetColumnHandle</code> that represents result
	 * set column object.
	 * 
	 * @return iterator over result set columns.
	 *