Clean up some code quality issues

This removes some qualifiers that aren't necessary (e.g. public/abstract on interfaces, private on enum constructors, final on private methods, static on nested interfaces/enums), uses Java 8 lambdas and features where that's an improvement

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=177182945

java/google/registry/flows/FlowComponent.java

@@ -122,7 +122,7 @@ public interface FlowComponent {
 
   /** Module to delegate injection of a desired {@link Flow}. */
   @Module
-  static class FlowComponentModule {
+  class FlowComponentModule {
     // WARNING: @FlowScope is intentionally omitted here so that we get a fresh Flow instance on
     // each call to Provider<Flow>.get(), to avoid Flow instance re-use upon transaction retries.
     // TODO(b/29874464): fix this in a cleaner way.

java/google/registry/flows/FlowReporter.java

@@ -14,6 +14,7 @@
 
 package google.registry.flows;
 
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static com.google.common.io.BaseEncoding.base64;
 import static google.registry.xml.XmlTransformer.prettyPrint;
 import static java.util.Collections.EMPTY_LIST;
@@ -22,6 +23,7 @@ import com.google.common.base.Ascii;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Streams;
 import google.registry.flows.FlowModule.ClientId;
 import google.registry.flows.FlowModule.InputXml;
 import google.registry.flows.annotations.ReportingSpec;
@@ -105,7 +107,7 @@ public class FlowReporter {
    * just about anything could be supplied, and there's no reason to validate twice when this just
    * needs to be roughly correct.
    */
-  private static final Optional<String> extractTld(String domainName) {
+  private static Optional<String> extractTld(String domainName) {
     int index = domainName.indexOf('.');
     return index == -1
         ? Optional.empty()
@@ -116,22 +118,19 @@ public class FlowReporter {
    * Returns the set of unique results of {@link #extractTld} applied to each given domain name,
    * excluding any absent results (i.e. cases where no TLD was detected).
    */
-  public static final ImmutableSet<String> extractTlds(Iterable<String> domainNames) {
-    ImmutableSet.Builder<String> set = new ImmutableSet.Builder<>();
-    for (String domainName : domainNames) {
-      Optional<String> extractedTld = extractTld(domainName);
-      if (extractedTld.isPresent()) {
-        set.add(extractedTld.get());
-      }
-    }
-    return set.build();
+  public static ImmutableSet<String> extractTlds(Iterable<String> domainNames) {
+    return Streams.stream(domainNames)
+        .map(FlowReporter::extractTld)
+        .filter(Optional::isPresent)
+        .map(Optional::get)
+        .collect(toImmutableSet());
   }
 
   /**
    * Returns the ICANN activity report field for the given flow class, or the empty string if no
    * activity report field specification is found.
    */
-  private static final String extractActivityReportField(Class<? extends Flow> flowClass) {
+  private static String extractActivityReportField(Class<? extends Flow> flowClass) {
     ReportingSpec reportingSpec = flowClass.getAnnotation(ReportingSpec.class);
     if (reportingSpec != null) {
       return reportingSpec.value().getFieldName();

java/google/registry/flows/ServerTridProvider.java

@@ -24,5 +24,5 @@ import google.registry.model.eppcommon.Trid;
 public interface ServerTridProvider {
 
   /** Creates a new server Trid. */
-  public String createServerTrid();
+  String createServerTrid();
 }

java/google/registry/flows/TransportCredentials.java

@@ -29,7 +29,7 @@ public interface TransportCredentials {
   void validate(Registrar registrar, String password) throws AuthenticationErrorException;
 
   /** Registrar password is incorrect. */
-  static class BadRegistrarPasswordException extends AuthenticationErrorException {
+  class BadRegistrarPasswordException extends AuthenticationErrorException {
     public BadRegistrarPasswordException() {
       super("Registrar password is incorrect");
     }

java/google/registry/flows/async/AsyncFlowMetrics.java

@@ -110,7 +110,7 @@ public class AsyncFlowMetrics {
 
     private final String metricLabelValue;
 
-    private OperationType(String metricLabelValue) {
+    OperationType(String metricLabelValue) {
       this.metricLabelValue = metricLabelValue;
     }
 
@@ -135,7 +135,7 @@ public class AsyncFlowMetrics {
 
     private final String metricLabelValue;
 
-    private OperationResult(String metricLabelValue) {
+    OperationResult(String metricLabelValue) {
       this.metricLabelValue = metricLabelValue;
     }
 

java/google/registry/flows/domain/DomainFlowUtils.java

@@ -509,9 +509,7 @@ public class DomainFlowUtils {
     // If the resultant autorenew poll message would have no poll messages to deliver, then just
     // delete it. Otherwise save it with the new end time.
     if (isAtOrAfter(updatedAutorenewPollMessage.getEventTime(), newEndTime)) {
-      if (autorenewPollMessage.isPresent()) {
-        ofy().delete().entity(autorenewPollMessage.get());
-      }
+      autorenewPollMessage.ifPresent(autorenew -> ofy().delete().entity(autorenew));
     } else {
       ofy().save().entity(updatedAutorenewPollMessage);
     }

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

@@ -207,9 +207,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
         autorenewEvent,
         gainingClientPollMessage,
         gainingClientAutorenewPollMessage);
-    if (billingEvent.isPresent()) {
-      entitiesToSave.add(billingEvent.get());
-    }
+    billingEvent.ifPresent(entitiesToSave::add);
     ofy().save().entities(entitiesToSave.build());
     // Delete the billing event and poll messages that were written in case the transfer would have
     // been implicitly server approved.

java/google/registry/flows/domain/DomainTransferRequestFlow.java

@@ -197,9 +197,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
             existingDomain,
             trid,
             gainingClientId,
-            (feesAndCredits.isPresent())
-                ? Optional.of(feesAndCredits.get().getTotalCost())
-                : Optional.empty(),
+            feesAndCredits.map(FeesAndCredits::getTotalCost),
             now);
     // Create the transfer data that represents the pending transfer.
     TransferData pendingTransferData =

java/google/registry/flows/domain/DomainUpdateFlow.java

@@ -193,9 +193,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
     entitiesToSave.add(newDomain, historyEntry);
     Optional<BillingEvent.OneTime> statusUpdateBillingEvent =
         createBillingEventForStatusUpdates(existingDomain, newDomain, historyEntry, now);
-    if (statusUpdateBillingEvent.isPresent()) {
-      entitiesToSave.add(statusUpdateBillingEvent.get());
-    }
+    statusUpdateBillingEvent.ifPresent(entitiesToSave::add);
     EntityChanges entityChanges =
         customLogic.beforeSave(
             BeforeSaveParameters.newBuilder()

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

@@ -113,15 +113,15 @@ public final class HostCreateFlow implements TransactionalFlow {
           ? new SubordinateHostMustHaveIpException()
           : new UnexpectedExternalHostIpException();
     }
-    HostResource newHost = new Builder()
-        .setCreationClientId(clientId)
-        .setPersistedCurrentSponsorClientId(clientId)
-        .setFullyQualifiedHostName(targetId)
-        .setInetAddresses(command.getInetAddresses())
-        .setRepoId(createRepoId(ObjectifyService.allocateId(), roidSuffix))
-        .setSuperordinateDomain(
-            superordinateDomain.isPresent() ? Key.create(superordinateDomain.get()) : null)
-        .build();
+    HostResource newHost =
+        new Builder()
+            .setCreationClientId(clientId)
+            .setPersistedCurrentSponsorClientId(clientId)
+            .setFullyQualifiedHostName(targetId)
+            .setInetAddresses(command.getInetAddresses())
+            .setRepoId(createRepoId(ObjectifyService.allocateId(), roidSuffix))
+            .setSuperordinateDomain(superordinateDomain.map(Key::create).orElse(null))
+            .build();
     historyBuilder
         .setType(HistoryEntry.Type.HOST_CREATE)
         .setModificationTime(now)

java/google/registry/flows/host/HostUpdateFlow.java

@@ -152,9 +152,8 @@ public final class HostUpdateFlow implements TransactionalFlow {
     AddRemove remove = command.getInnerRemove();
     checkSameValuesNotAddedAndRemoved(add.getStatusValues(), remove.getStatusValues());
     checkSameValuesNotAddedAndRemoved(add.getInetAddresses(), remove.getInetAddresses());
-    Key<DomainResource> newSuperordinateDomainKey = newSuperordinateDomain.isPresent()
-        ? Key.create(newSuperordinateDomain.get())
-        : null;
+    Key<DomainResource> newSuperordinateDomainKey =
+        newSuperordinateDomain.map(Key::create).orElse(null);
     // If the superordinateDomain field is changing, set the lastSuperordinateChange to now.
     DateTime lastSuperordinateChange =
         Objects.equals(newSuperordinateDomainKey, existingHost.getSuperordinateDomain())