wadl2java - Single WADL resources element is expected

Im not able to use wadl2java and I really need to convert my wadl's to java, it gives me the following exception: java.lang.IllegalStateException: Single WADL resources element is expected

I searched in the internet and found an answer to that problem but it doesn't work, since my namespace is correct.

what I found: How to create a client app for a RESTful service from wadl?

I have some projects from SoapUI and I tried to use the wadl2java tool that SoapUI has: https://www.soapui.org/rest-testing/code-generation.html I followed the instructions, downloaded the project, the project had some errors but resolved it thanks to the issue tracker. after configuring that, when I do the wadl2java in SoapUI it says success but doesn't do a thing...

I tried the maven plugin too that gives me the exception I said above.

I tried downloading the apache cxf and use the wadl2java but same as above...

is there any other way?