Use @XmlType.name and @XmlType.namespace to assign different names to them.

 原因是有2个类的namespace没有指定

 

 指定一下就可以了

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "sayHello", propOrder = {
    "arg0"
},namespace = "http://namespace.thats.not.the.same.as.the.generated")
public class SayHello {

    protected String arg0;