I'm getting ApexSuggestUsingNamedCred **Suggest named credentials for authentication** in Below Code.

 Blob headerValue = Blob.valueOf(username + ':' + password);
        String authorizationHeader = 'Basic ' + EncodingUtil.base64Encode(headerValue);
        system.debug('Encoder Value' + EncodingUtil.base64Encode(headerValue));
        http http = new http();
        httpRequest request = new httpRequest();
        request.setMethod('POST');
        request.setEndpoint(endpoint);
        request.setHeader('Content-Type', 'application/x-www-form-urlencoded');
        request.setHeader('Authorization', authorizationHeader);

There is no hard Coded value in My code, username and password is the input parameter for this method.

request.setHeader('Authorization', authorizationHeader); --> In Apex PMD report, Secutiry issue showing in this line.

Gone through this link, still can't able to find the cause. https://pmd.github.io/latest/pmd_rules_apex_security.html#apexsuggestusingnamedcred