@Entity
public class TestData implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    private String someName;
    @ManyToOne
    private DinamicProduct dinamicProduct;
    private Integer dinamicProductId;
.................

public class TestDataProvider implements Serializable {

    private static final long serialVersionUID = 1L;
    private List<TestData> testDatas = new ArrayList<TestData>();
    private MyDataSource pool = MyDataSource.INSTANCE;
    private final String columnsListForSQL = "id, someName, dinamicProduct, dinamicProductId";

    public TestData[] getTestDatas() throws SQLException {
        String sql = "select " + columnsListForSQL + " from TestData ";
        testDatas.clear();
        try (Connection c = pool.getDataSource().getConnection()) {
            try (PreparedStatement ps = c.prepareStatement(sql)) {
                try (ResultSet rs = ps.executeQuery()) {
                    while (rs.next()) {
                        testDatas.add(rsToTestData(rs));
                    }
                }
            }
        }
        return testDatas.toArray(new TestData[0]);
    }

    private TestData rsToTestData(ResultSet rs) throws SQLException {
        TestData td = new TestData();
        td.setId(rs.getInt("id"));
        td.setSomeName(rs.getString("someName"));
        td.setDinamicProduct( ????????????? );
        td.setDinamicProductId(rs.getInt("dinamicProductId"));
        return td;
    }