Add and wire up the AllocationTokenExtension XML class

The extension itself isn't used for anything yet; allocation tokens can be
passed for domain creates and checks but are ignored if present. This will
be changed in a subsequent CL that adds AllocationToken entities and related
logic. Usage of this extension in any other EPP flow will throw an
UnsupportedExtensionException.

The relevant spec is https://tools.ietf.org/html/draft-gould-allocation-token-04

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181343188

java/google/registry/flows/EppXmlTransformer.java

@@ -64,7 +64,8 @@ public class EppXmlTransformer  {
       "smd.xsd",
       "launch.xsd",
       "allocate.xsd",
-      "superuser.xsd");
+      "superuser.xsd",
+      "allocationToken-1.0.xsd");
 
   private static final XmlTransformer INPUT_TRANSFORMER =
       new XmlTransformer(SCHEMAS, EppInput.class);

java/google/registry/flows/domain/DomainCheckFlow.java

@@ -49,6 +49,7 @@ import google.registry.model.domain.fee.FeeCheckCommandExtension;
 import google.registry.model.domain.fee.FeeCheckCommandExtensionItem;
 import google.registry.model.domain.fee.FeeCheckResponseExtensionItem;
 import google.registry.model.domain.launch.LaunchCheckExtension;
+import google.registry.model.domain.token.AllocationTokenExtension;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.CheckData.DomainCheck;
@@ -118,7 +119,8 @@ public final class DomainCheckFlow implements Flow {
 
   @Override
   public EppResponse run() throws EppException {
-    extensionManager.register(FeeCheckCommandExtension.class, LaunchCheckExtension.class);
+    extensionManager.register(
+        FeeCheckCommandExtension.class, LaunchCheckExtension.class, AllocationTokenExtension.class);
     customLogic.beforeValidation();
     extensionManager.validate();
     validateClientIsLoggedIn(clientId);

java/google/registry/flows/domain/DomainCreateFlow.java

@@ -85,6 +85,7 @@ import google.registry.model.domain.launch.LaunchCreateExtension;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.domain.rgp.GracePeriodStatus;
 import google.registry.model.domain.secdns.SecDnsCreateExtension;
+import google.registry.model.domain.token.AllocationTokenExtension;
 import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppinput.ResourceCommand;
@@ -194,7 +195,8 @@ public class DomainCreateFlow implements TransactionalFlow {
         FeeCreateCommandExtension.class,
         SecDnsCreateExtension.class,
         MetadataExtension.class,
-        LaunchCreateExtension.class);
+        LaunchCreateExtension.class,
+        AllocationTokenExtension.class);
     customLogic.beforeValidation();
     extensionManager.validate();
     validateClientIsLoggedIn(clientId);

java/google/registry/flows/domain/DomainDeleteFlow.java

@@ -100,6 +100,7 @@ import org.joda.time.Duration;
 /**
  * An EPP flow that deletes a domain.
  *
+ * @error {@link google.registry.flows.EppException.UnimplementedExtensionException}
  * @error {@link google.registry.flows.ResourceFlowUtils.ResourceDoesNotExistException}
  * @error {@link google.registry.flows.ResourceFlowUtils.ResourceNotOwnedException}
  * @error {@link google.registry.flows.exceptions.OnlyToolCanPassMetadataException}