              }
  
          # ListField.
          if isinstance(field, serializers.ListField):
              return {
                  'type': 'array',
              }
  
          # DateField and DateTimeField type is string
          if isinstance(field, serializers.DateField):
 
</s> remove from rest_framework.fields import empty
 </s> add from rest_framework.fields import _UnvalidatedField, empty
            mapping = {
              }
  
          # ListField.
          if isinstance(field, serializers.ListField):
            mapping = {
                  'type': 'array',
              }
  
          # DateField and DateTimeField type is string
          if isinstance(field, serializers.DateField):
keep keep keep keep replace keep keep keep keep keep
 Added mapping of ListField.child type for OpenAPI Schemas. 
rest_framework/schemas/openapi.py