How to make a different string deserializer for different handles in Spring?

Question

Spring

Problem: empty strings ("") arrive in the request, as well as those consisting of only spaces.
Googled, added a simple deserializer to the config:

@Bean(name = JACKSON_MAPPER_BEAN_NAME)
    public ObjectMapper objectMapper(StatusNameResolver resolver) {
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule blankStringModule = new SimpleModule();

        blankStringModule.addDeserializer(
                String.class,
                new StdDeserializer<String>(String.class) {

                    @Override
                    public String deserialize(JsonParser parser, DeserializationContext context)
                            throws IOException {
                        String result = StringDeserializer.instance.deserialize(parser, context);
                        if (StringUtils.isBlank(result)) {
                            return null;
                        }
                        return result;
                    }
                });

        objectMapper.registerModule(blankStringModule);
        return objectMapper;
    }

The problem seemed to be gone, but in other requests everything broke down, since there this solution turned out to be unexpected.

Question: how to do the same, but for one specific method of the REST controller?