I have configured the wsdl2java goal to use wsdl-files from both local sources, using the <wsdl> element, and from maven artifacts, using the <wsdlArtifact> element. This fails unless I put the <wsdl> as the last <wsldOption>.
I have created a minimal testcase for this, unzip it and execute
$ mvn install:install-file -Dfile=greeter.wsdl -DgroupId=greeter -DartifactId=wsdl -Dversion=1.0 -Dpackaging=wsdl -DgeneratePom=true
to install the wsdl, then execute
$ mvn -e generate-sources
and it should fail. Then try reordering the wsdlOptions in the pom and it will not fail.