Bug 192083 [regression]DataException when preview attached xtab report.[1102]
data/org.eclipse.birt.report.data.adapter/src/org/eclipse/birt/report/data/adapter/impl/DataRequestSessionImpl.java
leafLevelKeyColumn,
			    new String[0] );
		}
	}
	
	/**
	 * 
	 * @param object
	 * @return
	 */
	private String[] toStringArray( List object )
	{
		String[] result = new String[object.size( )];
		for( int i = 0; i < object.size( ); i ++ )
		{
			result[i] = object.get( i ).toString();
		}
		return result;
	}
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.birt.report.data.adapter.api.DataRequestSession#prepare(org.eclipse.birt.data.engine.olap.api.query.ICubeQueryDefinition)
	 */
	public IPreparedCubeQuery prepare( ICubeQueryDefinition query )
			throws BirtException
	{
		return this.dataEngine.prepare( query, null );
	}
	/*
	 * (non-Javadoc)