When accessing a service that requires auth CXF returns: RuntimeException: Can't find input stream in message

I try to access a service that requires basic auth. My request does not include credentials. I would expect CXF to return something like
401 Authentication required. But it returns the following exception:

WARNUNG: Interceptor for

{http://customerservice.example.com/}

CustomerServiceService#

{http://customerservice.example.com/}

getCustomersByName has thrown exception, unwinding now
java.lang.RuntimeException: Can't find input stream in message
at org.apache.cxf.binding.soap.interceptor.ReadHeadersInterceptor.handleMessage(ReadHeadersInterceptor.java:116)
at org.apache.cxf.binding.soap.interceptor.ReadHeadersInterceptor.handleMessage(ReadHeadersInterceptor.java:60)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:255)
at org.apache.cxf.endpoint.ClientImpl.onMessage(ClientImpl.java:755)
at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponseInternal(HTTPConduit.java:2330)
at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponse(HTTPConduit.java:2192)
at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.close(HTTPConduit.java:2036)
at org.apache.cxf.transport.AbstractConduit.close(AbstractConduit.java:56)
at org.apache.cxf.transport.http.HTTPConduit.close(HTTPConduit.java:696)
at org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor.handleMessage(MessageSenderInterceptor.java:62)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:255)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:516)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:313)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:265)
at org.apache.cxf.frontend.ClientProxy.invokeSync(ClientProxy.java:73)
at org.apache.cxf.jaxws.JaxWsClientProxy.invoke(JaxWsClientProxy.java:124)
at $Proxy30.getCustomersByName(Unknown Source)
at client.JaxWsClient.main(JaxWsClient.java:24)