I am not sure what the cause is, but you may try to disable "serviceUnitAnalyzer" in pom.xml:

                                        (...)

Please also verify if your WSDL has no WS-I validation warnings.

This error usually occurs on a service unit (SU) and disabling the useServiceUnitAnalyzer should stop the error. The following is an example of how to disable it:

<plugin>
  <groupId>org.apache.servicemix.tooling</groupId>
  <artifactId>jbi-maven-plugin</artifactId>
  <version>${servicemix.version}</version>
  <extensions>true</extensions> 
  <configuration>
    <useServiceUnitAnalyzer>false</useServiceUnitAnalyzer>
  </configuration>                                
</plugin>

On a side note, this error on a service unit shouldn't actually be a problem as long as the full build succeeds as the jbi.xml file in a service unit is actually not used by ServiceMix.

Bruce