Switch from Guava Optionals to Java 8 Optionals

This was a surprisingly involved change. Some of the difficulties included
java.util.Optional purposely not being Serializable (so I had to move a
few Optionals in mapreduce classes to @Nullable) and having to add the Truth
Java8 extension library for assertion support.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171863777

javatests/google/registry/tools/params/BUILD

@@ -12,9 +12,10 @@ java_library(
         "//java/google/registry/model",
         "//java/google/registry/tools/params",
         "//javatests/google/registry/testing",
-        "//third_party/java/truth",
         "@com_beust_jcommander",
         "@com_google_guava",
+        "@com_google_truth",
+        "@com_google_truth_extensions_truth_java8_extension",
         "@joda_time",
         "@junit",
         "@org_hamcrest_library",

javatests/google/registry/tools/params/DateParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import google.registry.testing.ExceptionRule;
 import org.joda.time.DateTime;

javatests/google/registry/tools/params/DateTimeParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 import static org.joda.time.DateTimeZone.UTC;
 
 import com.beust.jcommander.ParameterException;

javatests/google/registry/tools/params/DurationParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import com.beust.jcommander.ParameterException;
 import google.registry.testing.ExceptionRule;

javatests/google/registry/tools/params/EnumParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import google.registry.model.registry.Registry.TldState;
 import google.registry.testing.ExceptionRule;

javatests/google/registry/tools/params/HostAndPortParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;

javatests/google/registry/tools/params/IntervalParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import com.beust.jcommander.ParameterException;
 import google.registry.testing.ExceptionRule;

javatests/google/registry/tools/params/KeyValueMapParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import com.google.common.collect.ImmutableMap;
 import google.registry.testing.ExceptionRule;

javatests/google/registry/tools/params/MoneyParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import com.beust.jcommander.ParameterException;
 import google.registry.testing.ExceptionRule;

javatests/google/registry/tools/params/PathParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;

javatests/google/registry/tools/params/PhoneNumberParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import google.registry.testing.ExceptionRule;
 import org.junit.Rule;
@@ -44,11 +45,11 @@ public class PhoneNumberParameterTest {
 
   @Test
   public void testConvert_empty_returnsAbsent() throws Exception {
-    assertThat(instance.convert("")).isAbsent();
+    assertThat(instance.convert("")).isEmpty();
   }
 
   @Test
   public void testConvert_nullString_returnsAbsent() throws Exception {
-    assertThat(instance.convert("null")).isAbsent();
+    assertThat(instance.convert("null")).isEmpty();
   }
 }

javatests/google/registry/tools/params/YearMonthParameterTest.java

@@ -15,6 +15,7 @@
 package google.registry.tools.params;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 
 import com.beust.jcommander.ParameterException;
 import google.registry.testing.ExceptionRule;