MultiSelect lookup in a SSRS report with BaseEnum

[
    DataContractAttribute,
    SysOperationContractProcessingAttribute(classstr(ENUMReportUIBuilder))
]
class ENUMReportDataContract implements SysOperationValidatable
{
    List 		ENUMTypeList;
}

[
    DataMemberAttribute('ENUMTypeList'),
    SysOperationDisplayOrderAttribute('1'),
    AifCollectionTypeAttribute('ENUMTypeList', Types::Enum, enumStr(ENUMType)),
    SysOperationLabelAttribute(literalstr("ENUM Label"))
]
public List parmENUMTypeList(List _ENUMTypeList = ENUMTypeList)
{
    ENUMTypeList = _ENUMTypeList;
    return ENUMTypeList;
}

UIBuilder class:

Class Declaration:

class ENUMReportUIBuilder extends SrsReportDataContractUIBuilder
{
    DialogField 		dfENUMType;
}

override methods:

public void postRun()
{
    super();
    dfENUMType= this.bindInfo().getDialogField(this.dataContractObject(), methodStr(ReportDataContract, parmENUMTypeList));
}

public void getFromDialog()
{
#SRSFramework
    ENUMReportDataContract  	contract = this.dataContractObject() as ENUMReportDataContract;
    str                         enumStrValue;
    List                        strSplitList;
    List                        retList = new List(Types::Enum);
    ListEnumerator              strSplitEnumerator;
    ENUMType            	ENUMTypeVar;
    super();
    strSplitList        = strSplit(dfENUMType.value(), #CollectionValueSeparator);
    strSplitEnumerator  = strSplitList.getEnumerator();
    while(strSplitEnumerator.moveNext())
    {
        enumStrValue = strSplitEnumerator.current();
        ENUMTypeVar = str2enum(ENUMTypeVar, enumStrValue);
        if (enum2str(ENUMTypeVar))
        {
            retList.addEnd(ENUMTypeVar);
        }
    }    contract.parmENUMTypeList(retList);
}