OkHttpClient

ApiModule.java

/**
     * Provides a Retrofit client that uses OkHttp for communication.
     *
     * @return {@link OkHttpClient}.
     */
    @Provides
    @Singleton
    OkHttpClient provideApiClient(AuthenticationInterceptor authenticationInterceptor) {
        OkHttpClient client = new OkHttpClient();
        client.interceptors().add(authenticationInterceptor);

        try {
            // Create a trust manager that does not validate certificate chains
            final TrustManager[] trustAllCerts = new TrustManager[]{new X509TrustManager() {
                @Override
                public void checkClientTrusted(
                        java.security.cert.X509Certificate[] chain,
                        String authType) throws CertificateException {
                }

                @Override
                public void checkServerTrusted(
                        java.security.cert.X509Certificate[] chain,
                        String authType) throws CertificateException {
                }

                @Override
                public java.security.cert.X509Certificate[] getAcceptedIssuers() {
                    return null;
                }
            }};

            // Install the all-trusting trust manager
            final SSLContext sslContext = SSLContext.getInstance("TLSv1");
            sslContext.init(null, trustAllCerts, new java.security.SecureRandom());

            // Create an ssl socket factory with our all-trusting manager
            final SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();
            client.setSslSocketFactory(sslSocketFactory);

            client.setHostnameVerifier(new HostnameVerifier() {
                @Override
                public boolean verify(String hostname, SSLSession session) {
                    return true;
                }
            });
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        
        return client;
    }

Did this ever work for you? I'm getting "Failed to validate the certificate chain, error: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found."