MinOccurs=0 ignored

When compiling the BPEL schema the elements of a process that are optionaled, are not created as optional.

Extract from the BPEL Schema:
<complexType name="Process">
<complexContent>
<extension base="bpws:ExtensibleElements">
<sequence>
<element name="partnerLinks" type="bpws:PartnerLinks"
minOccurs="0"/>
<element name="partners" type="bpws:Partners"
minOccurs="0"/>
<element name="variables"
type="bpws:Variables"
minOccurs="0"/>
<element name="correlationSets"
type="bpws:CorrelationSets" minOccurs="0"/>
<element name="faultHandlers" type="bpws:FaultHandlers"
minOccurs="0"/>
<element name="compensationHandler"
type="bpws:CompensationHandler" minOccurs="0"/>
<element name="eventHandlers"
type="bpws:EventHandlers" minOccurs="0"/>
<group ref="bpws:activity"/>
</sequence>
<attribute name="name" type="NCName"
use="required"/>
<attribute name="targetNamespace" type="anyURI"
use="required"/>
<attribute name="queryLanguage" type="anyURI"
default="http://www.w3.org/TR/1999/REC-xpath-19991116"/>
<attribute name="expressionLanguage" type="anyURI"
default="http://www.w3.org/TR/1999/REC-xpath-19991116"/>
<attribute name="suppressJoinFailure" type="bpws:Boolean"
default="no"/>
<attribute name="enableInstanceCompensation"
type="bpws:Boolean" default="no"/>
<attribute name="abstracProcess" type="bpws:Boolean"
default="no"/>
</extension>
</complexContent>
</complexType>

An empty process (inside a process document) now yields the following validation error:

Message: Expected elements 'partnerLinks@http://schemas.xmlsoap.org/ws/2003/03/business-process/ partners@http://schemas.xmlsoap.org/ws/2003/03/business-process/ variables@http://schemas.xmlsoap.org/ws/2003/03/business-process/ correlationSets@http://schemas.xmlsoap.org/ws/2003/03/business-process/ faultHandlers@http://schemas.xmlsoap.org/ws/2003/03/business-process/ compensationHandler@http://schemas.xmlsoap.org/ws/2003/03/business-process/ eventHandlers@http://schemas.xmlsoap.org/ws/2003/03/business-process/ empty@http://schemas.xmlsoap.org/ws/2003/03/business-process/ invoke@http://schemas.xmlsoap.org/ws/2003/03/business-process/ receive@http://schemas.xmlsoap.org/ws/2003/03/business-process/ reply@http://schemas.xmlsoap.org/ws/2003/03/business-process/ assign@http://schemas.xmlsoap.org/ws/2003/03/business-process/ wait@http://schemas.xmlsoap.org/ws/2003/03/business-process/ throw@http://schemas.xmlsoap.org/ws/2003/03/business-process/ terminate@http://schemas.xmlsoap.org/ws/2003/03/business-process/ flow@http://schemas.xmlsoap.org/ws/2003/03/business-process/ switch@http://schemas.xmlsoap.org/ws/2003/03/business-process/ while@http://schemas.xmlsoap.org/ws/2003/03/business-process/ sequence@http://schemas.xmlsoap.org/ws/2003/03/business-process/ pick@http://schemas.xmlsoap.org/ws/2003/03/business-process/ scope@http://schemas.xmlsoap.org/ws/2003/03/business-process/' at the end of the content in element process@http://schemas.xmlsoap.org/ws/2003/03/business-process/

Location of invalid XML: <xml-fragment/>

If necessary I can provide the generated source code and a test case.