code: private void processVersionField(PropertyMetadata propertyMetadata) {
      Class<?> dataClass = propertyMetadata.getDeclaredType();
      if (!long.class.equals(dataClass)) {
        String messageFormat = "Field %s in class %s must be of type %s";
        throw new EntityManagerException(String.format(messageFormat,
            propertyMetadata.getField().getName(), entityClass, long.class));
      }
      entityMetadata.setVersionMetadata(propertyMetadata);
    }
docs: Processes the Version annotation of the field with the given metadata.
  
  @param propertyMetadata
  the metadata of the field that has the Version annotation.