Improve error message when a node with an incorrectly configured cert…

…ificate attempts to connect

Updated the error message to understand what is the exact reason and renamed the API name to match the intention of API.

Resolves opensearch-project#4601

Signed-off-by: Abdul Muneer Kolarkunnu <muneer.kolarkunnu@netapp.com>

src/main/java/org/opensearch/security/ssl/util/ExceptionUtils.java

@@ -76,7 +76,7 @@ public static OpenSearchException createJwkCreationException(Throwable cause) {
         return new OpenSearchException("An error occurred during the creation of Jwk: {}", cause, cause.getMessage());
     }
 
-    public static OpenSearchException createTransportClientNoLongerSupportedException() {
-        return new OpenSearchException("Transport client authentication no longer supported.");
+    public static OpenSearchException clusterWrongNodeCertConfigException() {
+        return new OpenSearchException("Node certificate configuration is wrong or certificate is invalid.");
     }
 }

src/main/java/org/opensearch/security/transport/SecurityRequestHandler.java

@@ -290,7 +290,7 @@ protected void messageReceivedDecorate(
                     || HeaderHelper.isTrustedClusterRequest(getThreadContext())
                     || HeaderHelper.isExtensionRequest(getThreadContext()))) {
                     // CS-ENFORCE-SINGLE
-                    final OpenSearchException exception = ExceptionUtils.createTransportClientNoLongerSupportedException();
+                    final OpenSearchException exception = ExceptionUtils.clusterWrongNodeCertConfigException();
                     log.error(exception.toString());
                     transportChannel.sendResponse(exception);
                     return;