Copy Truth8.assertThat overloads for Optional and Stream to the…

… main `Truth` class.

(and prepare AutoValue tests for the new overloads, since the Eclipse compiler considers the (temporary!) signatures of `assertThat(Optional)` to be ambiguous)

We'll post some migration suggestions as part of the release notes.

This is the biggest part of #746.

RELNOTES=Added `assertThat` overloads for `Optional` and `Stream` to the main `Truth` class.
PiperOrigin-RevId: 598664192

core/src/main/java/com/google/common/truth/Truth.java

@@ -23,6 +23,8 @@
 import com.google.common.collect.Table;
 import java.math.BigDecimal;
 import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Stream;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -249,6 +251,18 @@ public static TableSubject assertThat(@Nullable Table<?, ?, ?> actual) {
     return assert_().that(actual);
   }
 
+  @SuppressWarnings("Java7ApiChecker") // no more dangerous that wherever the user got the Optional
+  @GwtIncompatible // creates ambiguities (Eclipse bug 577808 or similar?)
+  public static <T> OptionalSubject assertThat(@Nullable Optional<T> actual) {
+    return assert_().that(actual);
+  }
+
+  @SuppressWarnings("Java7ApiChecker") // no more dangerous that wherever the user got the Stream
+  @GwtIncompatible // creates ambiguities (Eclipse bug 577808 or similar?)
+  public static <T extends @Nullable Object> StreamSubject assertThat(@Nullable Stream<T> actual) {
+    return assert_().that(actual);
+  }
+
   /**
    * An {@code AssertionError} that (a) always supports a cause, even under old versions of Android
    * and (b) omits "java.lang.AssertionError:" from the beginning of its toString() representation.

core/src/test/java/com/google/common/truth/TruthAssertThatTest.java

@@ -25,8 +25,6 @@
 import com.google.common.reflect.TypeToken;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
-import java.util.Optional;
-import java.util.stream.Stream;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -47,9 +45,6 @@ public void staticAssertThatMethodsMatchStandardSubjectBuilderInstanceMethods()
     ImmutableSortedSet<TypeToken<?>> verbTypes =
         FluentIterable.from(asList(StandardSubjectBuilder.class.getMethods()))
             .filter(input -> input.getName().equals("that"))
-            // TODO: b/166630734 - Remove this when we add the assertThat overloads.
-            .filter(input -> input.getParameterTypes()[0] != Optional.class)
-            .filter(input -> input.getParameterTypes()[0] != Stream.class)
             .transform(TruthAssertThatTest::methodToReturnTypeToken)
             .toSortedSet(Ordering.usingToString());
     ImmutableSortedSet<TypeToken<?>> truthTypes =