fix: move url domain logic to EndpointContext

Author: diegomarquezp

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/rpc/ClientContext.java

@@ -271,12 +271,7 @@ public static ClientContext create(StubSettings settings) throws IOException {
     if (watchdogProvider != null && watchdogProvider.shouldAutoClose()) {
       backgroundResources.add(watchdog);
     }
-    String serviceName = endpointContext.serviceName();
-    String universeDomain = endpointContext.resolvedUniverseDomain();
-    String urlDomain = null;
-    if (!Strings.isNullOrEmpty(serviceName) && !Strings.isNullOrEmpty(universeDomain)) {
-      urlDomain = serviceName + "." + universeDomain;
-    }
+    String urlDomain = endpointContext.getUrlDomain();
 
     ApiTracerContext apiTracerContext =
         ApiTracerContext.newBuilder()

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/rpc/EndpointContext.java

@@ -140,6 +140,14 @@ public static EndpointContext getDefaultInstance() {
   @Nullable
   public abstract Integer resolvedServerPort();
 
+  @Nullable
+  String getUrlDomain() {
+    if (!Strings.isNullOrEmpty(serviceName()) && !Strings.isNullOrEmpty(resolvedUniverseDomain())) {
+      return serviceName() + "." + resolvedUniverseDomain();
+    }
+    return null;
+  }
+
   public abstract Builder toBuilder();
 
   public static Builder newBuilder() {

sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/rpc/EndpointContextTest.java

@@ -698,4 +698,31 @@ void endpointContextBuild_resolvesInvalidEndpointAndPort() throws Exception {
     Truth.assertThat(endpointContext.resolvedServerAddress()).isNull();
     Truth.assertThat(endpointContext.resolvedServerPort()).isNull();
   }
+
+  @Test
+  void getUrlDomain_success() throws IOException {
+    EndpointContext endpointContext = defaultEndpointContextBuilder.build();
+    Truth.assertThat(endpointContext.getUrlDomain()).isEqualTo("test.googleapis.com");
+  }
+
+  @Test
+  void getUrlDomain_nullServiceName() throws IOException {
+    EndpointContext endpointContext =
+        defaultEndpointContextBuilder.setServiceName(null).build();
+    Truth.assertThat(endpointContext.getUrlDomain()).isNull();
+  }
+
+  @Test
+  void getUrlDomain_emptyServiceName() throws IOException {
+    EndpointContext endpointContext =
+        defaultEndpointContextBuilder.setServiceName("").build();
+    Truth.assertThat(endpointContext.getUrlDomain()).isNull();
+  }
+
+  @Test
+  void getUrlDomain_nonGDUUniverseDomain() throws IOException {
+    EndpointContext endpointContext =
+        defaultEndpointContextBuilder.setUniverseDomain("random.com").build();
+    Truth.assertThat(endpointContext.getUrlDomain()).isEqualTo("test.random.com");
+  }
 }