Bug 201396 Exception is thrown out when a chart use the list shared result set [0005]
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryResults.java
public boolean isClosed( )
	{
		return queryService == null;
	}
	
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryService#getNestedLevel()
	 */
	public int getNestedLevel( )
	{
		return this.nestedLevel;
	}
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryService#getQueryScope()
	 */
	public Scriptable getQueryScope( )
	{
		return this.queryScope;
	}
	
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryService#getExecutorHelper()
	 */
	public IExecutorHelper getExecutorHelper( ) throws DataException
	{
		if ( this.getResultIterator( ) instanceof ResultIterator )
			return ( (ResultIterator) this.getResultIterator( ) ).getOdiResult( )
				.getExecutorHelper( );
		else
			return null;