WSDL validation reports errors for correct WSDL

I am seeing WSDL validation errors for WSDL that is correct. The following WSDL gives a validation error:

<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"
targetNamespace="http://helloworld"
xmlns:hw="http://helloworld"
name="helloworldws">

<component name="HelloWorldServiceComponent">
<service name="HelloWorldService">
<interface.java interface="helloworld.HelloWorldService"/>
<binding.ws uri="http://localhost:8085/HelloWorldService"/>
</service>
<implementation.java class="helloworld.HelloWorldImpl" />
</component>

</composite>

The validation error is as follows:

18-Sep-2007 12:10:56 org.apache.tuscany.sca.contribution.processor.ValidatingXMLStreamReader$1 error
WARNING: XMLSchema validation problem in:
file:/H:/tuscany52/sca-1.0/itest/ws-void-args-return/target/classes/helloworldws.composite, line: 30, column: 9
cvc-complex-type.2.4.a: Invalid content was found starting with element 'implementation.java'.
One of '

{"http://www.osoa.org/xmlns/sca/1.0":service, "http://www.osoa.org/xmlns/sca/1.0":reference, "http://www.osoa.org/xmlns/sca/1.0":property}

' is expected.

If the <implementation.java> line is moved before the <service> line, the error does not occur.