title: Django restframework, extra_kwargs not working
body: <p>I have a custom user model. I have created an api for user registration. Following is my serializer.</p>
  
  <pre><code>class UserSerializer(serializers.ModelSerializer):
      email = serializers.EmailField(
          required=True,
          validators=[
              UniqueValidator(queryset=get_user_model().objects.all())
          ]
      )
      password = serializers.CharField(min_length=8)
  
      class Meta:
          model = get_user_model()
          fields = ('email', 'password')
          extra_kwargs = {'password': {'write_only': True}, }
  
      def create(self, validated_data):
          email = validated_data.pop('email')
          password = validated_data.pop('password')
          user = get_user_model().objects.create_user(email, password, **validated_data)
          return user
  </code></pre>
  
  <p>Here is my view:</p>
  
  <pre><code>class Registration(generics.CreateAPIView):
      serializer_class = UserSerializer
      queryset = get_user_model().objects.all()
  </code></pre>
  
  <p>There are two inputs <code>email</code> and <code>password</code>. <code>password</code> field is given as write_only field. But after creating the user, the api returns the hashed password. How can I prevent the password being returned?</p>
  
  <p><a href="https://i.stack.imgur.com/OyTUr.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OyTUr.png" alt="enter image description here"></a></p>