Add back sslContext() to SslContextHandler. Used in tests.

Signed-off-by: Finn Carroll <carrofin@amazon.com>

Author: finnegancarroll

src/main/java/org/opensearch/security/ssl/OpenSearchSecureSettingsFactory.java

@@ -240,7 +240,7 @@ public Optional<SecureAuxTransportSettingsProvider> getSecureAuxTransportSetting
             @Override
             public Optional<SSLContext> buildSecureAuxServerTransportContext(Settings settings, AuxTransport transport) {
                 CertType auxCertType = new CertType(transport.settingKey());
-                return sslSettingsManager.sslContextHandler(auxCertType).map(SslContextHandler::sslContext);
+                return sslSettingsManager.sslContextHandler(auxCertType).map(SslContextHandler::tryFetchSSLContext);
             }
 
             @Override

src/main/java/org/opensearch/security/ssl/SslContextHandler.java

@@ -67,16 +67,24 @@ public SslConfiguration sslConfiguration() {
     }
 
     /**
-     * Only JDK provider is supported, so we expect only JdkSslContext.
-     * @return null if context cannot be fetched from io.netty.handler.ssl.SslContext child type.
+     * Attempt to fetch the underlying io.netty.handler.ssl.SslContext as a javax SSLContext.
+     * As JDK is the only supported provider we expect sslContext is always of type JdkSslContext,
+     * allowing us to extract the javax.net.ssl.SSLContext delegate. Providing a javax SSLContext is
+     * desirable for dependencies which want to access security settings without taking on netty as a dependency.
+     * @return null if context cannot be fetched as JdkSslContext.
      */
-    public SSLContext sslContext() {
+    public SSLContext tryFetchSSLContext() {
         if (sslContext instanceof JdkSslContext) {
             return ((JdkSslContext) sslContext).context();
         }
         return null;
     }
 
+    // public for testing
+    public SslContext sslContext() {
+        return sslContext;
+    }
+
     public Stream<Certificate> certificates() {
         return Stream.concat(authorityCertificates(), keyMaterialCertificates())
             .sorted((c1, c2) -> Boolean.compare(c1.hasPrivateKey(), c2.hasPrivateKey()));