How to add headers to OkHttp request interceptor?

I have this interceptor that i add to my OkHttp client:

public class RequestTokenInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
  Request request = chain.request();
  // Here where we'll try to refresh token.
  // with an retrofit call
  // After we succeed we'll proceed our request
  Response response = chain.proceed(request);
  return response;
}
}

How can i add headers to request in my interceptor?

I tried this but i am making mistake and i lose my request when creating new request:

    public class RequestTokenInterceptor implements Interceptor {
    @Override
    public Response intercept(Interceptor.Chain chain) throws IOException {
        Request request = chain.request();
        Request newRequest;

        try {
            Log.d("addHeader", "Before");
            String token = TokenProvider.getInstance(mContext).getToken();
            newRequest = request.newBuilder()
                    .addHeader(HeadersContract.HEADER_AUTHONRIZATION, O_AUTH_AUTHENTICATION + token)
                    .addHeader(HeadersContract.HEADER_CLIENT_ID, CLIENT_ID)
                    .build();
        } catch (Exception e) {
            Log.d("addHeader", "Error");
            e.printStackTrace();
            return chain.proceed(request);
        }

        Log.d("addHeader", "after");
        return chain.proceed(newRequest);
    }
}

Note that, i know i can add header when creating request like this:

Request request = new Request.Builder()
    .url("https://api.github.com/repos/square/okhttp/issues")
    .header("User-Agent", "OkHttp Headers.java")
    .addHeader("Accept", "application/json; q=0.5")
    .addHeader("Accept", "application/vnd.github.v3+json")
    .build();

But it doesn't fit my needs. I need it in interceptor.

The key is to use the old request object to create the newBuilder()

Finally, I added the headers this way:

@Override
    public Response intercept(Interceptor.Chain chain) throws IOException {
        Request request = chain.request();
        Request newRequest;

        newRequest = request.newBuilder()
                .addHeader(HeadersContract.HEADER_AUTHONRIZATION, O_AUTH_AUTHENTICATION)
                .addHeader(HeadersContract.HEADER_X_CLIENT_ID, CLIENT_ID)
                .build();
        return chain.proceed(newRequest);
    }

Alternatively, you can add using .headers() function with a header object. For instance:

request.newBuilder()
.headers(Headers.of(
  "Authorization:", " Basic <credentials>"
  "Content-Type:", " text/html; charset=utf-8"
  ...
))

Warning: The number of http-hearder-field must be an even number.