  from django.utils.encoding import force_text
  
  from rest_framework import exceptions, serializers
  from rest_framework.compat import uritemplate
  
  from .generators import BaseSchemaGenerator
  from .inspectors import ViewInspector
  from .utils import get_pk_description, is_list_view
  
 
</s> remove             serializers.DecimalField: 'number',
            serializers.FloatField: 'number',
            serializers.IntegerField: 'integer',

 </s> add 
from rest_framework.fields import empty
  from django.utils.encoding import force_text
  
  from rest_framework import exceptions, serializers
  from rest_framework.compat import uritemplate
from rest_framework.fields import empty
  
  from .generators import BaseSchemaGenerator
  from .inspectors import ViewInspector
  from .utils import get_pk_description, is_list_view
  
keep keep keep add keep keep keep keep keep
 Generate OpenAPI schema field types from validators. (#6674) 
rest_framework/schemas/openapi.py