JPA + StoredProcedureCall + object type IN parameter = problem

[czajah]

I'm trying to do a simple thing: call stored procedure which have a object type parameter.

This is what I have in db:

    create or replace
    TYPE TEST_TYPE AS OBJECT 
    (
      test_field varchar(100)
    )

and

    CREATE OR REPLACE PROCEDURE TEST_PROC 
    (
      PARAM1 IN TEST_TYPE 
    ) AS 
    BEGIN
    END TEST_PROC;

This is what I have in my java code:

    @Embeddable
    @Struct(name = "TEST_TYPE", fields = {"TEST_FIELD"})
    public class TestStruct
    {
    
        private String testField;
    
        public String getTestField() {
            return testField;
        }

        public void setTestField(String testField) {
            this.testField = testField;
        }
    }

and

        @PostConstruct
        public void init()
        {
    
            StoredProcedureCall call = new StoredProcedureCall();
            call.setProcedureName("TEST_PROC");
            call.addNamedArgument("PARAM1", "PARAM1", Types.STRUCT, "TEST_TYPE", TestStruct.class);
    
            DataReadQuery dataReadQuery = new DataReadQuery(call);
            dataReadQuery.addArgument("PARAM1");
    
            TestStruct testStruct = new TestStruct();
            List args = new ArrayList();
            args.add(testStruct);
    
            Object result = ((EntityManagerImpl)em.getDelegate()).getSession().executeQuery(dataReadQuery,args);
        }

this is what I get in runtime:

    Internal Exception: java.sql.SQLException: Invalid column type
    Error Code: 17004
    Call: BEGIN TEST_PROC(PARAM1=>?); END;
        bind => [1 parameter bound]
    Query: DataReadQuery()

I think I totally don't understand the subject of usage structs with JPA

please help me, good people :)

What is the shortest way to make this working?