Bug 181121 Model should provide utility method for cube to get correspond dimension key.
In model cube handle, the relation of cube data set and dimension data sets are managed by a series of dimension condition handles.We need model to add utility method so that we can easily get corresponding dimension data set column names according to given cube dimension keys.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/elements/structures/DimensionCondition.java
{
			if ( value instanceof String )
				hierarchy = new ElementRefValue( StringUtil
						.extractNamespace( (String) value ), StringUtil
						.extractName( (String) value ) );
			else if ( value instanceof Hierarchy )
				hierarchy = new ElementRefValue( null, (Hierarchy) value );
			else
				hierarchy = (ElementRefValue) value;
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.core.IStructure#getStructName()
	 */
	public String getStructName( )
	{
		return DIMENSION_CONDITION_STRUCT;
	}
	/**
	 * Sets the primary key list for this dimension condition.
	 * 
	 * @param keys
	 *            the key list to set
	 */
	public void setPrimaryKeys( List keys )
	{
		setProperty( PRIMARY_KEYS_MEMBER, keys );
	}