private X509TrustManager trustManager(X509Certificate ca) throws Exception {
        KeyStore keyStore = TestKeyStore.createKeyStore();
        keyStore.setCertificateEntry("alias", ca);

        return new TrustManagerImpl(keyStore);
    }
Ensure that our non-standard behavior of learning to trust new
intermediate CAs does not regress. http://b/3404902
common/src/test/java/org/conscrypt/TrustManagerImplTest.java