CertificatePinner -

CertificatePinner.java

 CertificatePinner certificatePinner = new CertificatePinner.Builder()
                    .add("api.github.com", "sha256/6wJsqVDF8K19zxfLxV5DGRneLyzso9adVdUN/exDacw=")
                    .build();
 final OkHttpClient client = httpBuilder.certificatePinner(certificatePinner).build();
 
  Retrofit retrofit = new Retrofit.Builder()
                    .baseUrl(END_POINT)
                    .addConverterFactory(GsonConverterFactory.create())
                    .client(client)
                    .build();