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
switch ( refType )
		{
			case PROPERTY :
			case PROPERTY_LISTn :
			case PROPERTY_MEMBER :
				return propDefn.getStructDefn( );
			case PROPERTY_LISTn_MEMBER :
			case PROPERTY_LISTn_MEMBER_MEMBER :
			case PROPERTY_LISTn_MEMBER_LISTn :
			case PROPERTY_LISTn_MEMBER_LISTn_MEMBER :
			case PROPERTY_MEMBER_MEMBER :
			case PROPERTY_MEMBER_LISTn_MEMBER :
			case PROPERTY_MEMBER_LISTn :
				return member[0].getStructDefn( );
			default :
				assert false;
				return null;
		}
	}
	/**
	 * Returns the list index pointed to by this reference.
	 * <p>
	 * property.member.list[ <strong>n </strong> ][.member] <br>
	 * 
	 * property.list[ <strong>n </strong>][.member] <br>
	 * property.list[n].member.list[ <strong>n </strong>][.member]
	 * 
	 * @return the list index pointed to by this reference
	 */
	public int getIndex( )