Data Member Attribute is not supported on extension class

Hi All,

We have done some customisation on class LedgerChartOfAccountContract (its a DataContractAttribute) and added some DataMemberAttribute.

Now as part of AX 7 migration we are planing to create an extension class and trying to move the customised data member attribute to the new extended class.

[ExtensionOf(classStr(LedgerChartOfAccountContract))]

public final class LedgerChartOfAccountContract_Extension
{
private boolean cnfExclNonTransMainAccount;

[
DataMemberAttribute(identifierStr(cnfExclNonTransMainAccount))
]

public boolean parmcnfExclNonTransMainAccount(boolean _exclNonTransMainAccount = cnfExclNonTransMainAccount)
{
       cnfExclNonTransMainAccount = _exclNonTransMainAccount;
       return cnfExclNonTransMainAccount;
}

}

Getting the compilation error "The Data Member Attribute is not supported on extension class"

Please suggest some alternate ways to move the data member attribute to a new class\extended class.

Thanks

Anoop