eclipselink/Moxy : inheritance and attribute name oveloading based on type

Question

I'm facing a marshalling/unmarshalling problem involving inheritance and polymorphism using MOXy's JAXB implementation and external metadata bindings file.

I have no control on the XML files or the model classes.

There are multiple classes inside the model that inherit other DTO classes. Here is an example of the environment I'm working in. This example is only here for some syntax purpose, the real environment involves nested inheritance, collections etc. :

Here is the class that will be inherited

  class A {

        private String name;

        public String getName(){
              return name;
        }

        public void setName(String value){
              name = value;
        }

  } 

Here is one inherited class

  class B extends A {

        private String attrFromB;

        public String getAttrFromB(){
              return attrFromB;
        }

        public void setAttrFromB(String value){
              attrFromB = value;
        }
  } 

And another

  class C extends A {

        private String attrFromC;

        public String getAttrFromC(){
              return attrFromC;
        }

        public void setAttrFromC(String value){
              attrFromC= value;
        }
  } 

Here is a container class

  class MyContainerClass{

        private A myObject;

        public A getMyObject(){
           return myObject;
        }

        public void setMyObject(A value){
           myObject = value;
        }
  }

Here is the XML that it should produce in the case of MyContainer containing A

  <MyContainer>
        <MyObject nameA="foo" />
  </MyContainer>

MyContainer containing B

  <MyContainer>
        <MyObject nameB="foo" attrFromB="bar" />
  </MyContainer>

And MyContainer containing C

  <MyContainer>
        <MyObject nameC="foo" attrFromC="bar" />
  </MyContainer>

So you can already see problems in the horizon...

Here is the mapping file that I would write :

  <?xml version="1.0"?>
     <xml-bindings 
        xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
        package-name="com.test.example"
        version="2.1">  

        <java-type name="A" xml-accessor-type="NONE">
           <xml-root-element name="MyObject" />
           <java-attributes>
              <xml-element java-attribute="name" xml-path="@nameA" />
           </java-attributes>
        </java-type>  

        <java-type name="B" xml-accessor-type="NONE">
           <xml-root-element name="MyObject" />
           <xml-see-also>
              com.test.example.A
           </xml.see.also>
           <java-attributes>
              <xml-element java-attribute="name" xml-path="@nameB" />
              <xml-element java-attribute="attrFromB" xml-path="@attrFromB" />
           </java-attributes>
        </java-type>

        <java-type name="C" xml-accessor-type="NONE">
           <xml-root-element name="MyObject" />
           <xml-see-also>
              com.test.example.A
           </xml.see.also>
           <java-attributes>
              <xml-element java-attribute="name" xml-path="@nameC" />
              <xml-element java-attribute="attrFromC" xml-path="@attrFromC" />
           </java-attributes>
        </java-type>

        <java-type name="MyContainer" xml-accessor-type="NONE">
           <xml-root-element name="MyContainer" />
           <java-attributes>
              <xml-element java-attribute="myObject" type="com.test.example.A" xml-path="MyObject" />
           </java-attributes>
        </java-type>

     </xml-bindings>

---

The first problem is that if I bind the classes like that, I get the following exception :

  [Exception [EclipseLink-44] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DescriptorException
  Exception Description: Missing class indicator field from database row [UnmarshalRecord()].

1st question : I understand that this is normal, Jaxb needs some way to determine the type of MyContaioner.myObject attribute. The problem is that I have no access to the incoming XML files, so I cant add xsi:type fields to them. Is there a way to determine a class based on the presence of a specific attribute in it ? regardless of it's value. If the source xml contains a @attrFromC attribute, I know the object should be of type C. If it contains attrFromB, it's B.

---

The second problem is that the "name" attribute doesn't exist inside B and C, so jaxb ignores em.

  --Ignoring attribute [name] on class [com.test.example.B] as no Property was generated for it.
  --Ignoring attribute [name] on class [com.test.example.C] as no Property was generated for it.

2nd question : The other problem is that I dont know if Jaxb is capable of overriding xml attribute names like it is expected inside the XML file (@nameA, @nameB and nameC all referring to A.name), is there a way to do it ?

Thanks in advance for your time.