refactor(gax-httpjson): configure Conscrypt NetHttpTransport for default transport in ManagedHttpJsonChannel

Author: lqiu96

sdk-platform-java/gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/ManagedHttpJsonChannel.java

@@ -71,7 +71,12 @@ private ManagedHttpJsonChannel(
     this.executor = executor;
     this.usingDefaultExecutor = usingDefaultExecutor;
     this.endpoint = endpoint;
-    this.httpTransport = httpTransport == null ? new NetHttpTransport() : httpTransport;
+    this.httpTransport =
+        httpTransport == null
+            ? HttpJsonTransportUtils.configureConscryptSecurityProvider(
+                    new NetHttpTransport.Builder())
+                .build()
+            : httpTransport;
     this.deadlineScheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
   }
 
@@ -227,11 +232,14 @@ public ManagedHttpJsonChannel build() {
         usingDefaultExecutor = true;
       }
 
-      return new ManagedHttpJsonChannel(
-          executor,
-          usingDefaultExecutor,
-          endpoint,
-          httpTransport == null ? new NetHttpTransport() : httpTransport);
+      if (httpTransport == null) {
+        httpTransport =
+            HttpJsonTransportUtils.configureConscryptSecurityProvider(
+                    new NetHttpTransport.Builder())
+                .build();
+      }
+
+      return new ManagedHttpJsonChannel(executor, usingDefaultExecutor, endpoint, httpTransport);
     }
   }
 }