chore: address comments.

samples/snippets/src/main/java/com/example/spanner/v2/CreateDatabaseWithDefaultLeaderSample.java

@@ -32,7 +32,7 @@ public class CreateDatabaseWithDefaultLeaderSample {
 
   static void createDatabaseWithDefaultLeader() throws IOException {
     // TODO(developer): Replace these variables before running the sample.
-    final String instanceName = "my-instance-name";
+    final String instanceName = "projects/my-project/instances/my-instance-id";
     final String databaseId = "my-database-name";
     final String defaultLeader = "my-default-leader";
     createDatabaseWithDefaultLeader(instanceName, databaseId, defaultLeader);

samples/snippets/src/main/java/com/example/spanner/v2/CreateInstanceExample.java

@@ -18,7 +18,6 @@
 
 //[START spanner_create_instance]
 import com.google.api.gax.longrunning.OperationFuture;
-import com.google.cloud.spanner.SpannerExceptionFactory;
 import com.google.cloud.spanner.admin.instance.v1.InstanceAdminClient;
 import com.google.cloud.spanner.admin.instance.v1.InstanceAdminSettings;
 import com.google.spanner.admin.instance.v1.CreateInstanceMetadata;
@@ -72,10 +71,8 @@ static void createInstance(String projectId, String instanceId) throws IOExcepti
       System.out.printf(
           "Error: Creating instance %s failed with error message %s%n",
           instance.getName(), e.getMessage());
-      throw SpannerExceptionFactory.asSpannerException(e);
     } catch (InterruptedException e) {
       System.out.println("Error: Waiting for createInstance operation to finish was interrupted");
-      throw SpannerExceptionFactory.propagateInterrupt(e);
     }
   }
 }

samples/snippets/src/test/java/com/example/spanner/v2/CreateInstanceSampleIT.java

@@ -32,7 +32,7 @@ public void testCreateInstance() throws Exception {
 
     // Runs sample
     final String out = SampleRunner.runSample(() ->
-        CreateInstanceSample.createInstance(projectId, instanceId)
+        CreateInstanceExample.createInstance(projectId, instanceId)
     );
 
     assertTrue(