Bug 183579 Model need hold on DimensionConditionHandle and DimensionJoinConditionHandle signleton or overwrites the equals and hashcode method
The Dataset Joint Editor need join two Editparts which have the same model. But the DimensionConditionHandle and the DimensionJoinConditionHandle are create a new instance erery time when I get them. So model need hold on them signleton or overwrites the equals and hashcode method.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/MemberRef.java
return member[0].isList( );
			case PROPERTY_MEMBER_MEMBER :
			case PROPERTY_MEMBER_LISTn_MEMBER :
			case PROPERTY_LISTn_MEMBER_LISTn_MEMBER :
			case PROPERTY_LISTn_MEMBER_MEMBER :
				return member[1].isList( );
			default :
				return false;
		}
	}
	/**
	 * Returns the structure at the given position in structure list.
	 * 
	 * @param list
	 *            structure list
	 * @param level
	 *            the structure position in first index or second index
	 * @return structure if the position is in list range, otherwise, return
	 *         null.
	 */
	Structure getStructure( List list, int level )
	{
		assert level == 0 || level == 1;
		if ( list == null )
			return null;
		if ( index[level] < 0 || index[level] >= list.size( ) )
			return null;
		return (Structure) list.get( index[level] );
	}
}