Spring boot LDAP auth in rest API without spring security

I have an API that is consumed by a mobile application that goes something like this:

    @PostMapping("/myAPI")
    public String getAgentProductsList(@RequestParam String username, @RequestParam String password, @RequestParam String productType) {
        /*
            here I need to verify the username and password in LDAP and retrieve the user's related data
         */

        /*
            some more code
         */
        return "some products related to the user authenticated previously";
    }

I need to do the authentication without using spring security or any redirection (that's what I've found in almost all the basic tutorial out there). So authenticating the username/password must happen inside the my endpoint.

That's my first time with LDAP so any helpful links or explinations is highly appreciated.