Bug 188052 Enhance the behavior of DimensionConditionHandle
Current in model implementation, there could be multiple DimensionConditionHandle corresponding to one dimension. This will cause problem for both UI and DtE. What we expect is that for each dimension, there are only one DimensionConditionHandle accompany with. Model should merge all the duplicate DimensionConditionHandle so that when UI/DtE is using model API the we can get unique DimensionConditionHandle for each dimension.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/olap/TabularCubeHandle.java
* @param handle
	 *            the handle of the data set
	 * 
	 * @throws SemanticException
	 *             if the property is locked, or the data-set is invalid.
	 */
	public void setDataSet( DataSetHandle handle ) throws SemanticException
	{
		if ( handle == null )
			setStringProperty( DATA_SET_PROP, null );
		else
		{
			ModuleHandle moduleHandle = handle.getRoot( );
			String valueToSet = handle.getElement( ).getFullName( );
			if ( moduleHandle instanceof LibraryHandle )
			{
				String namespace = ( (LibraryHandle) moduleHandle )
						.getNamespace( );
				valueToSet = StringUtil.buildQualifiedReference( namespace,
						valueToSet );
			}
			setStringProperty( DATA_SET_PROP, valueToSet );
		}
	}
	/**
	 * Adds a dimension condition to this cube.
	 * 
	 * @param condition
	 * @return the added dimension condition handle if succeed
	 * @throws SemanticException