What am I missing here?

Class ECUH.BPL.ClassMethods.X509CredentialAlias Extends %String
{

Parameter VALUELIST As COSEXPRESSION = "..GetValueList()";

ClassMethod GetValueList() As %String
{
	Set sql = "SELECT LIST(Alias) As ValueList FROM %SYS.X509Credentials"
	Set resultSet = ##class(%SQL.Statement).%ExecDirect(,sql)

	If (resultSet.%Next())
	{
		Return $char(34) _ "," _ resultSet.ValueList _ $char(34)
	}
	Return ""
}

}

This currently returns:

Not sure I understand how a method can be passed into a COSEXPRESSION even after reading the ref. materials.

I now have an issue with the App settings list within the Business Process not updating once a cert is removed from the certificate credentials manager. If I add a cert, it reflects in the list but once removed, the cert alias stays in the settings list. Any ideas on how I can update the property list that's being stored to reflect the current list state?

This worked perfectly. I had  modify the string output of GetValueList() to wrap the list in quotes like this:  ",Flight Vector,test"

ClassMethod GetValueList() As %String
{
	Set sql = "SELECT LIST(Alias) As ValueList FROM %SYS.X509Credentials"
	Set resultSet = ##class(%SQL.Statement).%ExecDirect(,sql)

	If (resultSet.%Next())
	{   
		Return $char(34) _ "," _ resultSet.ValueList _ $char(34)
	}
	Return ""
}