Hibernate 5 : generator class=“sequence” not working

after upgrade hibernate 4 to 5 sequence not working and hibernate get next val from hibernate_sequence  but 

I solved it by re-configuring mapping in the HBM file from:

<generator class="sequence">

           <param name="sequence">PRODUCT_ID_SEQ</param>

</generator>

to:

<generator class="org.hibernate.id.enhanced.SequenceStyleGenerator">

          <param name="prefer_sequence_per_entity">true</param>

          <param name="optimizer">none</param>

          <param name="increment_size">1</param>

          <param name="sequence_name">PRODUCT_ID_SEQ</param>

</generator> 

ref:http://stackoverflow.com/questions/2155376/how-to-use-existing-oracle-sequence-to-generate-id-in-hibernate