code: private Mapper createCustomMapper(Field field, PropertyMapper propertyMapperAnnotation) {
      Class<? extends Mapper> mapperClass = propertyMapperAnnotation.value();
      Constructor<? extends Mapper> constructor = IntrospectionUtils.getConstructor(mapperClass,
          Field.class);
      if (constructor != null) {
        try {
          return constructor.newInstance(field);
        } catch (Exception exp) {
          throw new EntityManagerException(exp);
        }
      }
      throw new EntityManagerException(
          String.format("Mapper class %s must have a public constructor with a parameter type of %s",
              mapperClass.getName(), Field.class.getName()));
  
    }
docs: Creates and returns a custom mapper for the given field.
  
  @param field
  the field
  @param propertyMapperAnnotation
  property mapper annotation that specifies the mapper class
  @return custom mapper for the given field