fix: S2A- Check if a default endpoint has been set (#3784)

Certain handwritten client libraries set this field to the (TLS)
endpoint via
[`GrpcTransportOptions.setUpChannelProvider`](https://github.com/googleapis/sdk-platform-java/blob/2a41393c0e148e96fd3a0a8e1505e0827aa4fd3a/java-core/google-cloud-core-grpc/src/main/java/com/google/cloud/grpc/GrpcTransportOptions.java#L165).

This isn't really a custom endpoint, so we should be able to use S2A
when this is set.

Example with Cloud Logging:
https://github.com/googleapis/java-logging/blob/644ebd756d44ffc02b58aa30d9a07c8afe700981/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/GrpcLoggingRpc.java#L137

Author: rmehta19

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

@@ -327,8 +327,12 @@ boolean shouldUseS2A() {
       }
 
       // If a custom endpoint is being used, skip S2A.
-      if (!Strings.isNullOrEmpty(clientSettingsEndpoint())
-          || !Strings.isNullOrEmpty(transportChannelProviderEndpoint())) {
+      if ((!Strings.isNullOrEmpty(clientSettingsEndpoint())
+              && !buildEndpointTemplate(serviceName(), resolvedUniverseDomain())
+                  .contains(clientSettingsEndpoint()))
+          || (!Strings.isNullOrEmpty(transportChannelProviderEndpoint())
+              && !buildEndpointTemplate(serviceName(), resolvedUniverseDomain())
+                  .contains(transportChannelProviderEndpoint()))) {
         return false;
       }
 

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

@@ -380,6 +380,7 @@ void endpointContextBuild_shouldUseS2A_tlsEndpoint() throws IOException {
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setUsingGDCH(false);
@@ -478,6 +479,7 @@ void shouldUseS2A_envVarNotSet_returnsFalse() throws IOException {
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setUsingGDCH(false);
@@ -491,6 +493,7 @@ void shouldUseS2A_UsingGDCH_returnsFalse() throws IOException {
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setUsingGDCH(true);
@@ -504,6 +507,7 @@ void shouldUseS2A_customEndpointSetViaClientSettings_returnsFalse() throws IOExc
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("test.endpoint.com:443")
             .setTransportChannelProviderEndpoint("")
             .setUsingGDCH(false);
@@ -517,6 +521,7 @@ void shouldUseS2A_customEndpointSetViaTransportChannelProvider_returnsFalse() th
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("test.endpoint.com:443")
             .setUsingGDCH(false);
@@ -530,6 +535,7 @@ void shouldUseS2A_mtlsEndpointNull_returnsFalse() throws IOException {
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setUsingGDCH(false)
@@ -544,6 +550,7 @@ void shouldUseS2A_mtlsEndpointEmpty_returnsFalse() throws IOException {
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setMtlsEndpoint("")
@@ -558,6 +565,7 @@ void shouldUseS2A_mtlsEndpointNotGoogleDefaultUniverse_returnsFalse() throws IOE
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setMtlsEndpoint("test.mtls.abcd.com:443")
@@ -572,6 +580,7 @@ void shouldUseS2A_success() throws IOException {
     defaultEndpointContextBuilder =
         defaultEndpointContextBuilder
             .setEnvProvider(envProvider)
+            .setResolvedUniverseDomain(Credentials.GOOGLE_DEFAULT_UNIVERSE)
             .setClientSettingsEndpoint("")
             .setTransportChannelProviderEndpoint("")
             .setUsingGDCH(false);