@InitBinder in spring boot not working with @RequestBody

This is an old question, but I've managed to get the @InitBinder annotation to bind my custom Validator to a @Valid @RequestBody parameter like this:

@InitBinder
private void bindMyCustomValidator(WebDataBinder binder) {
    if ("entityList".equals(binder.getObjectName())) {
        binder.addValidators(new MyCustomValidator());
    }
}

If you try to filter the bound argument by setting the value of the annotation, then it won't work for a @RequestBody argument. So here I check the object name instead. My method parameter is actually called entities, but Spring had decided to call it entityList. I had to debug it to discover this.

From the docs,

Default is to apply to all command/form attributes and all request parameters processed by the annotated handler class. Specifying model attribute names or request parameter names here restricts the init-binder method to those specific attributes/parameters, with different init-binder methods typically applying to different groups of attributes or parameters.

Please have a look here

You can try my solution:

@InitBinder
private void initBinder(WebDataBinder binder) {
    if (CustomerQuickRegisterEntity.class.equals(binder.getTarget().getClass())) {
        binder.addValidators(new YourValidator());
    }
}