diff --git a/sshd-common/src/main/java/org/apache/sshd/common/config/keys/OpenSshCertificate.java b/sshd-common/src/main/java/org/apache/sshd/common/config/keys/OpenSshCertificate.java
index 8fcc8aa..525c4f6 100644
--- a/sshd-common/src/main/java/org/apache/sshd/common/config/keys/OpenSshCertificate.java
+++ b/sshd-common/src/main/java/org/apache/sshd/common/config/keys/OpenSshCertificate.java
@@ -56,7 +56,7 @@
     }
 
     /**
-     * The minimal {@link #getValidAfter()} or {@link #getValidBefore()} value, corresponding to {@link Instant#EPOCH}.
+     * The minimal {@link #getValidAfter()} or {@link #getValidBefore()} value, corresponding to {@code Instant#EPOCH}.
      */
     long MIN_EPOCH = 0L;
 
diff --git a/sshd-common/src/main/java/org/apache/sshd/common/util/buffer/Buffer.java b/sshd-common/src/main/java/org/apache/sshd/common/util/buffer/Buffer.java
index 396a64b..55e419f 100644
--- a/sshd-common/src/main/java/org/apache/sshd/common/util/buffer/Buffer.java
+++ b/sshd-common/src/main/java/org/apache/sshd/common/util/buffer/Buffer.java
@@ -812,6 +812,7 @@
      * Then the entire name + data strings are added as bytes (which will get a length prefix)
      *
      * @param options to write into the buffer, may be {@code null} or empty but must not contain {@code null} elements
+     * @param charset The {@link Charset} to use for string options
      */
     public void putCertificateOptions(List<OpenSshCertificate.CertificateOption> options, Charset charset) {
         int numObjects = GenericUtils.size(options);
diff --git a/sshd-core/src/main/java/org/apache/sshd/certificate/OpenSshCertificateBuilder.java b/sshd-core/src/main/java/org/apache/sshd/certificate/OpenSshCertificateBuilder.java
index 6a25a71..5070e73 100644
--- a/sshd-core/src/main/java/org/apache/sshd/certificate/OpenSshCertificateBuilder.java
+++ b/sshd-core/src/main/java/org/apache/sshd/certificate/OpenSshCertificateBuilder.java
@@ -126,7 +126,8 @@
     /**
      * If null, uses {@link OpenSshCertificate#MIN_EPOCH}
      *
-     * @param validAfter {@link Instant} to use for validBefore
+     * @param  validAfter {@link Instant} to use for validBefore
+     * @return            Self reference
      */
     public OpenSshCertificateBuilder validAfter(Instant validAfter) {
         if (validAfter == null) {
@@ -145,7 +146,8 @@
     /**
      * If null, uses {@link OpenSshCertificate#INFINITY}
      *
-     * @param validBefore {@link Instant} to use for validBefore
+     * @param  validBefore {@link Instant} to use for validBefore
+     * @return             Self reference
      */
     public OpenSshCertificateBuilder validBefore(Instant validBefore) {
         if (validBefore == null) {
diff --git a/sshd-core/src/test/java/org/apache/sshd/certificates/OpenSSHCertificateParserTest.java b/sshd-core/src/test/java/org/apache/sshd/certificates/OpenSSHCertificateParserTest.java
index ebf16d3..adcb0be 100644
--- a/sshd-core/src/test/java/org/apache/sshd/certificates/OpenSSHCertificateParserTest.java
+++ b/sshd-core/src/test/java/org/apache/sshd/certificates/OpenSSHCertificateParserTest.java
@@ -62,25 +62,27 @@
                 new TestParams("rsa-sha2-512", "user01_ecdsa_521"));
     }
 
+    @SuppressWarnings("synthetic-access")
     private String getCertificateResource() {
         return USER_KEY_PATH + params.privateKey + "-cert.pub";
     }
 
     @Test
-    public void parseCertificate() throws Exception {
+    @SuppressWarnings("synthetic-access")
+    public void testParseCertificate() throws Exception {
 
         try (InputStream certInputStream
                 = Thread.currentThread().getContextClassLoader().getResourceAsStream(getCertificateResource())) {
 
-            final byte[] certBytes = IoUtils.toByteArray(certInputStream);
-            final String certLine = GenericUtils.replaceWhitespaceAndTrim(new String(certBytes, StandardCharsets.UTF_8));
+            byte[] certBytes = IoUtils.toByteArray(certInputStream);
+            String certLine = GenericUtils.replaceWhitespaceAndTrim(new String(certBytes, StandardCharsets.UTF_8));
 
-            final PublicKeyEntry certPublicKeyEntry = PublicKeyEntry.parsePublicKeyEntry(certLine);
-            final PublicKey cert = certPublicKeyEntry.resolvePublicKey(null, null, null);
+            PublicKeyEntry certPublicKeyEntry = PublicKeyEntry.parsePublicKeyEntry(certLine);
+            PublicKey cert = certPublicKeyEntry.resolvePublicKey(null, null, null);
 
             assertObjectInstanceOf("Must be OpenSshCertificate instance", OpenSshCertificate.class, cert);
 
-            final OpenSshCertificate typedCert = (OpenSshCertificate) cert;
+            OpenSshCertificate typedCert = (OpenSshCertificate) cert;
 
             assertEquals(Collections.singletonList("user01"), typedCert.getPrincipals());
             assertEquals(OpenSshCertificate.Type.USER, typedCert.getType());
@@ -116,7 +118,6 @@
     }
 
     private static class TestParams {
-
         private final String sigAlgorithm;
         private final String privateKey;
 
@@ -124,7 +125,5 @@
             this.sigAlgorithm = sigAlgorithm;
             this.privateKey = privateKey;
         }
-
     }
-
 }
diff --git a/sshd-core/src/test/java/org/apache/sshd/common/forward/PortForwardingLoadTest.java b/sshd-core/src/test/java/org/apache/sshd/common/forward/PortForwardingLoadTest.java
index 1bbe342..57f7e7f 100644
--- a/sshd-core/src/test/java/org/apache/sshd/common/forward/PortForwardingLoadTest.java
+++ b/sshd-core/src/test/java/org/apache/sshd/common/forward/PortForwardingLoadTest.java
@@ -497,7 +497,8 @@
             resp.append("0123456789\n");
         }
         resp.append("</body></html>\n");
-        final StringBuilder sb = new StringBuilder();
+
+        StringBuilder sb = new StringBuilder();
         sb.append("HTTP/1.1 200 OK").append('\n');
         sb.append("Content-Type: text/HTML").append('\n');
         sb.append("Content-Length: ").append(resp.length()).append('\n');
@@ -512,25 +513,26 @@
         });
         acceptor.setReuseAddress(true);
         acceptor.bind(new InetSocketAddress(0));
-        final int port = acceptor.getLocalAddress().getPort();
+        int port = acceptor.getLocalAddress().getPort();
 
         Session session = createSession();
         try {
-            final int forwardedPort1 = session.setPortForwardingL(0, host, port);
-            final int forwardedPort2 = CoreTestSupportUtils.getFreePort();
+            int forwardedPort1 = session.setPortForwardingL(0, host, port);
+            int forwardedPort2 = CoreTestSupportUtils.getFreePort();
             session.setPortForwardingR(forwardedPort2, TEST_LOCALHOST, forwardedPort1);
             outputDebugMessage("URL: http://localhost %s", forwardedPort2);
 
-            final CountDownLatch latch = new CountDownLatch(nbThread * nbDownloads * nbLoops);
-            final Thread[] threads = new Thread[nbThread];
-            final List<Throwable> errors = new CopyOnWriteArrayList<>();
+            CountDownLatch latch = new CountDownLatch(nbThread * nbDownloads * nbLoops);
+            Thread[] threads = new Thread[nbThread];
+            List<Throwable> errors = new CopyOnWriteArrayList<>();
             for (int i = 0; i < threads.length; i++) {
                 threads[i] = new Thread(getCurrentTestName() + "[" + i + "]") {
                     @Override
+                    @SuppressWarnings("synthetic-access")
                     public void run() {
                         for (int j = 0; j < nbLoops; j++) {
-                            final MultiThreadedHttpConnectionManager mgr = new MultiThreadedHttpConnectionManager();
-                            final HttpClient client = new HttpClient(mgr);
+                            MultiThreadedHttpConnectionManager mgr = new MultiThreadedHttpConnectionManager();
+                            HttpClient client = new HttpClient(mgr);
                             client.getHttpConnectionManager().getParams().setDefaultMaxConnectionsPerHost(100);
                             client.getHttpConnectionManager().getParams().setMaxTotalConnections(1000);
                             for (int i = 0; i < nbDownloads; i++) {