public HttpResponse sampleRequest() throws Exception {
    HttpClient httpclient = new DefaultHttpClient();
    HttpGet httpget = new HttpGet("https://server.com/path?apikey=123");
    HttpResponse response = httpclient.execute(httpget);
    return response;
}

To this:

public HttpResponse strongSampleRequest() throws Exception {
    StrongHttpsClient httpclient = new StrongHttpsClient(context);
    ch.boye.httpclientandroidlib.client.methods.HttpGet httpget = new HttpGet(
        "https://server.com/path?apikey=123");
    HttpResponse response = httpclient.execute();
    return response;
  }

In your code, change the imports from org.apache.http.* to ch.boye.httpclientandroidlib.*. The HttpGet and HttpResponse objects used by OnionKit are from another library called httpclientandroidlib (also included in OnionKit). httpclientandroidlib is a repackaging of HttpClient 4.2.3 for Android, which includes updates and bug fixes over the standard HttpClient library included in Android SDK.

httpclient.getStrongTrustManager().setNotifyVerificationFail(true)

This is a useful feature for notifying users that there has been an issue with the verification, and also that the Internet resource they are currently connected to is unsafe.

httpclient.getStrongTrustManager().setVerifyChain(true);

Enabling verifyChain ensures when the TrustManager.checkServerTrusted server(…) method is called while making an HTTPS connection that the whole certificate chain is validated. This setting is enabled by default.

httpclient.getStrongTrustManager().setCheckChainCrypto(true);

This checks the certificate chain for instances where an issuer has used an MD5 algorithm, which is considered weak and should be avoided. This setting is enabled by default.