Fix various Error Prone errors that were found by the FOSS build

Most common:
- Unnecessary parentheses and operator precedence clarify (self-explanatory)
- Reference equality--there were a few instances of using == or != improperly
- Qualification of Builder (and similar) imports so that it's clear which type of Builder we're referring to
- Marking some immutable classes with @Immutable since EP desires that all enums be deeply immutable
- String.split() having "surprising behavior"

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=230971531

java/google/registry/flows/contact/ContactCreateFlow.java

@@ -31,7 +31,6 @@ import google.registry.flows.TransactionalFlow;
 import google.registry.flows.annotations.ReportingSpec;
 import google.registry.model.contact.ContactCommand.Create;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.contact.ContactResource.Builder;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.CreateData.ContactCreateData;
@@ -71,19 +70,20 @@ public final class ContactCreateFlow implements TransactionalFlow {
     Create command = (Create) resourceCommand;
     DateTime now = ofy().getTransactionTime();
     verifyResourceDoesNotExist(ContactResource.class, targetId, now);
-    ContactResource newContact = new Builder()
-        .setContactId(targetId)
-        .setAuthInfo(command.getAuthInfo())
-        .setCreationClientId(clientId)
-        .setPersistedCurrentSponsorClientId(clientId)
-        .setRepoId(createRepoId(ObjectifyService.allocateId(), roidSuffix))
-        .setFaxNumber(command.getFax())
-        .setVoiceNumber(command.getVoice())
-        .setDisclose(command.getDisclose())
-        .setEmailAddress(command.getEmail())
-        .setInternationalizedPostalInfo(command.getInternationalizedPostalInfo())
-        .setLocalizedPostalInfo(command.getLocalizedPostalInfo())
-        .build();
+    ContactResource newContact =
+        new ContactResource.Builder()
+            .setContactId(targetId)
+            .setAuthInfo(command.getAuthInfo())
+            .setCreationClientId(clientId)
+            .setPersistedCurrentSponsorClientId(clientId)
+            .setRepoId(createRepoId(ObjectifyService.allocateId(), roidSuffix))
+            .setFaxNumber(command.getFax())
+            .setVoiceNumber(command.getVoice())
+            .setDisclose(command.getDisclose())
+            .setEmailAddress(command.getEmail())
+            .setInternationalizedPostalInfo(command.getInternationalizedPostalInfo())
+            .setLocalizedPostalInfo(command.getLocalizedPostalInfo())
+            .build();
     validateAsciiPostalInfo(newContact.getInternationalizedPostalInfo());
     validateContactAgainstPolicy(newContact);
     historyBuilder

java/google/registry/flows/contact/ContactUpdateFlow.java

@@ -39,7 +39,6 @@ import google.registry.flows.exceptions.ResourceHasClientUpdateProhibitedExcepti
 import google.registry.model.contact.ContactCommand.Update;
 import google.registry.model.contact.ContactCommand.Update.Change;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.contact.ContactResource.Builder;
 import google.registry.model.contact.PostalInfo;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppcommon.AuthInfo;
@@ -109,7 +108,7 @@ public final class ContactUpdateFlow implements TransactionalFlow {
         .setXmlBytes(null)  // We don't want to store contact details in the history entry.
         .setParent(Key.create(existingContact));
     checkSameValuesNotAddedAndRemoved(statusesToAdd, statusToRemove);
-    Builder builder = existingContact.asBuilder();
+    ContactResource.Builder builder = existingContact.asBuilder();
     Change change = command.getInnerChange();
     // The spec requires the following behaviors:
     //   * If you update part of a postal info, the fields that you didn't update are unchanged.

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

@@ -62,7 +62,6 @@ import google.registry.flows.custom.EntityChanges;
 import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainBase.Builder;
 import google.registry.model.domain.GracePeriod;
 import google.registry.model.domain.fee.BaseFee.FeeType;
 import google.registry.model.domain.fee.Credit;
@@ -149,7 +148,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
     flowCustomLogic.afterValidation(
         AfterValidationParameters.newBuilder().setExistingDomain(existingDomain).build());
     ImmutableSet.Builder<ImmutableObject> entitiesToSave = new ImmutableSet.Builder<>();
-    Builder builder;
+    DomainBase.Builder builder;
     if (existingDomain.getStatusValues().contains(StatusValue.PENDING_TRANSFER)) {
       builder =
           denyPendingTransfer(existingDomain, TransferStatus.SERVER_CANCELLED, now, clientId)

java/google/registry/flows/domain/DomainRestoreRequestFlow.java

@@ -46,7 +46,6 @@ import google.registry.flows.annotations.ReportingSpec;
 import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.OneTime;
-import google.registry.model.billing.BillingEvent.OneTime.Builder;
 import google.registry.model.billing.BillingEvent.Reason;
 import google.registry.model.domain.DomainBase;
 import google.registry.model.domain.DomainCommand.Update;
@@ -258,7 +257,7 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow  {
         .build();
   }
 
-  private Builder prepareBillingEvent(HistoryEntry historyEntry, Money cost, DateTime now) {
+  private OneTime.Builder prepareBillingEvent(HistoryEntry historyEntry, Money cost, DateTime now) {
     return new BillingEvent.OneTime.Builder()
         .setTargetId(targetId)
         .setClientId(clientId)

java/google/registry/flows/domain/DomainTransferApproveFlow.java

@@ -191,7 +191,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
             .setAutorenewPollMessage(Key.create(gainingClientAutorenewPollMessage))
             // Remove all the old grace periods and add a new one for the transfer.
             .setGracePeriods(
-                (billingEvent.isPresent())
+                billingEvent.isPresent()
                     ? ImmutableSet.of(
                         GracePeriod.forBillingEvent(GracePeriodStatus.TRANSFER, billingEvent.get()))
                     : ImmutableSet.of())

java/google/registry/flows/host/HostCreateFlow.java

@@ -45,7 +45,6 @@ import google.registry.model.eppoutput.CreateData.HostCreateData;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.host.HostCommand.Create;
 import google.registry.model.host.HostResource;
-import google.registry.model.host.HostResource.Builder;
 import google.registry.model.index.EppResourceIndex;
 import google.registry.model.index.ForeignKeyIndex;
 import google.registry.model.ofy.ObjectifyService;
@@ -119,7 +118,7 @@ public final class HostCreateFlow implements TransactionalFlow {
           : new UnexpectedExternalHostIpException();
     }
     HostResource newHost =
-        new Builder()
+        new HostResource.Builder()
             .setCreationClientId(clientId)
             .setPersistedCurrentSponsorClientId(clientId)
             .setFullyQualifiedHostName(targetId)

java/google/registry/flows/host/HostInfoFlow.java

@@ -32,7 +32,6 @@ import google.registry.model.domain.DomainBase;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.host.HostInfoData;
-import google.registry.model.host.HostInfoData.Builder;
 import google.registry.model.host.HostResource;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.util.Clock;
@@ -72,7 +71,7 @@ public final class HostInfoFlow implements Flow {
     if (isLinked(Key.create(host), now)) {
       statusValues.add(StatusValue.LINKED);
     }
-    Builder hostInfoDataBuilder = HostInfoData.newBuilder();
+    HostInfoData.Builder hostInfoDataBuilder = HostInfoData.newBuilder();
     // Hosts transfer with their superordinate domains, so for hosts with a superordinate domain,
     // the client id, last transfer time, and pending transfer status need to be read off of it. If
     // there is no superordinate domain, the host's own values for these fields will be correct.