netty: push sslContext initialization into transportCreationParamsFilterFactory

netty/src/main/java/io/grpc/netty/NettyChannelBuilder.java

@@ -432,7 +432,6 @@ public final class NettyChannelBuilder
     private final Class<? extends Channel> channelType;
     private final Map<ChannelOption<?>, ?> channelOptions;
     private final NegotiationType negotiationType;
-    private final SslContext sslContext;
     private final EventLoopGroup group;
     private final boolean usingSharedGroup;
     private final int flowControlWindow;
@@ -452,23 +451,10 @@ public final class NettyChannelBuilder
       this.channelType = channelType;
       this.negotiationType = negotiationType;
       this.channelOptions = new HashMap<ChannelOption<?>, Object>(channelOptions);
-      if (negotiationType == NegotiationType.TLS && sslContext == null) {
-        try {
-          sslContext = GrpcSslContexts.forClient().build();
-        } catch (SSLException ex) {
-          throw new RuntimeException(ex);
-        }
-      }
-      this.sslContext = sslContext;
 
       if (transportCreationParamsFilterFactory == null) {
-        transportCreationParamsFilterFactory = new TransportCreationParamsFilterFactory() {
-          @Override
-          public TransportCreationParamsFilter create(
-              SocketAddress targetServerAddress, String authority, String userAgent) {
-            return new DynamicNettyTransportParams(targetServerAddress, authority, userAgent);
-          }
-        };
+        transportCreationParamsFilterFactory =
+            new DefaultNettyTransportCreationParamsFilterFactory(sslContext);
       }
       this.transportCreationParamsFilterFactory = transportCreationParamsFilterFactory;
 
@@ -523,6 +509,27 @@ public final class NettyChannelBuilder
       }
     }
 
+    private final class DefaultNettyTransportCreationParamsFilterFactory
+        implements TransportCreationParamsFilterFactory {
+      private final SslContext sslContext;
+
+      private DefaultNettyTransportCreationParamsFilterFactory(SslContext sslContext) {
+        if (negotiationType == NegotiationType.TLS && sslContext == null) {
+          try {
+            sslContext = GrpcSslContexts.forClient().build();
+          } catch (SSLException ex) {
+            throw new RuntimeException(ex);
+          }
+        }
+        this.sslContext = sslContext;
+      }
+
+      @Override
+      public TransportCreationParamsFilter create(
+          SocketAddress targetServerAddress, String authority, String userAgent) {
+        return new DynamicNettyTransportParams(targetServerAddress, authority, userAgent);
+      }
+
       @CheckReturnValue
       private final class DynamicNettyTransportParams implements TransportCreationParamsFilter {
 
@@ -559,3 +566,4 @@ public final class NettyChannelBuilder
       }
     }
   }
+}