              if field.write_only:
                  schema['writeOnly'] = True
              if field.allow_null:
                  schema['nullable'] = True
  
              properties[field.field_name] = schema
          return {
              'required': required,
              'properties': properties,
          }
 
</s> remove             serializers.DecimalField: 'number',
            serializers.FloatField: 'number',
            serializers.IntegerField: 'integer',

 </s> add 
            if field.default and field.default != empty:  # why don't they use None?!
                schema['default'] = field.default
            if field.help_text:
                schema['description'] = field.help_text
            self._map_field_validators(field.validators, schema)
              if field.write_only:
                  schema['writeOnly'] = True
              if field.allow_null:
                  schema['nullable'] = True
            if field.default and field.default != empty:  # why don't they use None?!
                schema['default'] = field.default
            if field.help_text:
                schema['description'] = field.help_text
            self._map_field_validators(field.validators, schema)
  
              properties[field.field_name] = schema
          return {
              'required': required,
              'properties': properties,
          }
keep keep keep add keep keep keep keep keep keep
 Generate OpenAPI schema field types from validators. (#6674) 
rest_framework/schemas/openapi.py