Remove always null call for Certificate Credentials

Explicitly setting this to null for clarity. This also reduces the
parameters needed to construct a client.

src/main/java/org/jenkinsci/plugins/stashNotifier/StashNotifier.java

@@ -459,8 +459,6 @@ protected Collection<String> lookupCommitSha1s(
     protected CloseableHttpClient getHttpClient(PrintStream logger, Run<?, ?> run, String stashServer) throws Exception {
         DescriptorImpl globalSettings = getDescriptor();
 
-        CertificateCredentials certificateCredentials = getCredentials(CertificateCredentials.class, run.getParent());
-
         final int timeoutInMilliseconds = 60_000;
 
         RequestConfig.Builder requestBuilder = RequestConfig.custom()
@@ -477,7 +475,7 @@ protected CloseableHttpClient getHttpClient(PrintStream logger, Run<?, ?> run, S
         if (url.getProtocol().equals("https") && ignoreUnverifiedSSL) {
             // add unsafe trust manager to avoid thrown SSLPeerUnverifiedException
             try {
-                SSLContext sslContext = buildSslContext(ignoreUnverifiedSSL, certificateCredentials);
+                SSLContext sslContext = buildSslContext(ignoreUnverifiedSSL, null);
                 SSLConnectionSocketFactory sslConnSocketFactory = new SSLConnectionSocketFactory(
                         sslContext,
                         new String[]{"TLSv1", "TLSv1.1", "TLSv1.2"},