I created my mapping.xml and wsdl file with wscompile. Now it works. Before this I've created the files with Java2WSDL. Althaugh it seems to work for single custom type, for arrays it does not work, because of the Java2WSDL command, I guess. During generating the client-files the IDE created an additional client-file called arrayOf_xsd_xxx.
I don't know for what this file is - it does not matter because by using wscompile it works without this arrayOf_xsd_xxx files.