Retrofit2 interceptor to add headers to HTTP requests

AddHeaderInterceptor.java

public class AddHeaderInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {

        Request.Builder builder = chain.request().newBuilder();
        builder.addHeader("Authorization", "headerContent");

        return chain.proceed(builder.build());
    }
}

Usage

    OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
    httpClient.addNetworkInterceptor(new AddHeaderInterceptor());
    httpClient.addInterceptor(new LogJsonInterceptor());
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(getEndPoint())
            .addConverterFactory(GsonConverterFactory.create())
            .client(httpClient.build())
            .build();

What is the difference between addNetworkInterpector() and addInterceptor() ?

Difference is documented at: https://github.com/square/okhttp/wiki/Interceptors