I have been using the Google OAuth for some of my projects at work for a while. A recent request was to add custom user-agent strings to different apps for the people doing analytics on which apps are using the authentication servers. I have some functions that do custom HTTP Get calls using the Bearer token we get from the OAuth flow, then the library also does its own calls behind the scene. I was able to add a user-agent to my calls easily, but the under the hood ones the library does kept coming up as “Google-HTTP-Java-Client/1.34.2 (gzip)”. I tried a few different ways, and at the same time was searching online, and didn’t see anyone speaking about this. Below is a quick block to put into your app if you want to set the user-agent.

These are the current versions of the OAuth library, and the http client I have been using to do auth.

compile group: 'com.google.oauth-client', name: 'google-oauth-client', version: '1.31.4'
compile group: 'com.google.oauth-client', name: 'google-oauth-client-servlet', version: '1.31.4'
compile group: 'com.google.http-client', name: 'google-http-client', version: '1.39.0'
compile group: 'com.google.http-client', name: 'google-http-client-jackson2', version: '1.39.0'

For my setup, I have the OAuth Servlet that initializes the OAuth flow, then a second servlet which handles the callback; as documented here. I added to the “class OauthCallback extends AbstractAuthorizationCodeCallbackServlet” the following ConnectionFactory under the override for the initializeFlow() function. Replace “myApp-v1.0.1” with your app name. Hope this helps someone!

@Override
protected final AuthorizationCodeFlow initializeFlow() throws IOException {
    ConnectionFactory connectionFactory = url -> {
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
        httpURLConnection.setRequestProperty("user-agent", "myApp-v1.0.1");
        return httpURLConnection;
    };
    return new AuthorizationCodeFlow.Builder(BearerToken.authorizationHeaderAccessMethod(),
            new NetHttpTransport.Builder().setConnectionFactory(connectionFactory).build(),
            new JacksonFactory(),
            .... (code removed);
}