java - JPA2.0 How to map a collection of an entity with inheritance mapped by TABLE_PER_CLASS -

i want map collection (a map) of entity inheritance. entity , inheriting entity that:

@entity public class testentity {      @onetomany(mappedby = "parent")     public map<string, mapvalueentity> map          = new hashmap<string, mapvalueentity>();      @id     @generatedvalue(strategy = auto)     protected long id;      public string name;      public testentity() {     }      public testentity(string name) {         this.name = name;     } }  @entity public class subentity extends testentity{      public subentity() {     }      string testsubentityname;      public subentity(string name) {         this.testsubentityname = name;     } } 

the entity used map value this

@entity public class mapvalueentity {      testentity parent;      @id     @generatedvalue(strategy = auto)     protected long id;      public mapvalueentity() {     }      string subentityname;      public mapvalueentity(string name) {         this.subentityname = name;     } } 

and here test code:

entitymanager em = entitymanagerservice.getentitymanager(); em.gettransaction().begin();  (int = 0; < 10; i++) {     testentity e = new testentity("mynameis" + i);         (int j = 0; j < 8; j++) {             mapvalueentity se = new mapvalueentity("iamno" + j + "." + i);             e.map.put("key" + * 100 + j, se);             se.parent = e;             em.persist(se);         }         em.persist(e);     }  em.gettransaction().commit(); 

so far works fine. eclipselink puts testentity , subentity in 1 table discriminator column distinguishing between classes. , complete map data stored in table mapvalueentity. if change mapping strategy default (= single_table) table_per_class construction breaks:

@entity @inheritance(strategy = table_per_class) public class testentity { ... 

the exception description says:

multiple writable mappings exist field [mapvalueentity.map_key]. 1 may defined writable, others must specified read-only.

do see chance use table_per_class strategy in scenario? mentioned "multiple writable mappings"?