java: raise an exception on conversion of unknown polymorphic types i…

…n Java SDK

Rather than silently succeeding (returning None), raise an exception.

This brings the Java SDK in line with the behaviour of the Go SDK.

Includes some rudimentary test coverage to demonstrate this works for one of those types.

JAVADEPS was updated solely for the change of io.grpc from a runtime to an
implementation dependency for the tests, which was required to construct a GRPC
exception to exercise the exception conversion code.

GitOrigin-RevId: 6743b0e76616eaee0e9fe1f8583bd4f123092a5b

com/strongdm/api/plumbing/Plumbing.java

@@ -880,7 +880,7 @@ public static com.strongdm.api.Account convertAccountToPorcelain(Account plumbin
     if (plumbing.hasUser()) {
       return convertUserToPorcelain(plumbing.getUser());
     }
-    return null;
+    throw new UnknownException("unknown polymorphic type, please upgrade your SDK");
   }
 
   public static Account convertAccountToPlumbing(com.strongdm.api.Account porcelain) {
@@ -5707,7 +5707,7 @@ public static com.strongdm.api.Node convertNodeToPorcelain(Node plumbing) {
     if (plumbing.hasRelay()) {
       return convertRelayToPorcelain(plumbing.getRelay());
     }
-    return null;
+    throw new UnknownException("unknown polymorphic type, please upgrade your SDK");
   }
 
   public static Node convertNodeToPlumbing(com.strongdm.api.Node porcelain) {
@@ -7118,7 +7118,7 @@ public static com.strongdm.api.Resource convertResourceToPorcelain(Resource plum
     if (plumbing.hasTeradata()) {
       return convertTeradataToPorcelain(plumbing.getTeradata());
     }
-    return null;
+    throw new UnknownException("unknown polymorphic type, please upgrade your SDK");
   }
 
   public static Resource convertResourceToPlumbing(com.strongdm.api.Resource porcelain) {
@@ -8274,7 +8274,7 @@ public static com.strongdm.api.SecretStore convertSecretStoreToPorcelain(SecretS
     if (plumbing.hasVaultToken()) {
       return convertVaultTokenStoreToPorcelain(plumbing.getVaultToken());
     }
-    return null;
+    throw new UnknownException("unknown polymorphic type, please upgrade your SDK");
   }
 
   public static SecretStore convertSecretStoreToPlumbing(com.strongdm.api.SecretStore porcelain) {