Soap wash_out gem disable nillable values

Question

I am using wash_out gem in rails 3.2.22

When buiding a complex type ex: 'AuditCase'

I use the following defenition:

class AuditCase < WashOut::Type
   map :caseID => :long,
       :periodStart => :dateTime,
end

And it gives me the following result

<xsd:complexType name="AuditCase">
   <xsd:sequence>
      <xsd:element name="CaseID" type="xsd:long" nillable="true"/>
      <xsd:element name="PeriodStart" type="xsd:dateTime" nillable="true"/>
   </xsd:sequence>
</xsd:complexType>

How can i configure this WashOut::Type, 'AuditCase' to set the nill parameter to false: nillable="false" ?