Update docs to reflect that the Java 8 assertions have "moved" to the…

… main `Truth` class.

This includes deprecating the old class.

This continues work on #746.

RELNOTES=Deprecated `Truth8`. All its functionality is now supported through the main `Truth` API.
PiperOrigin-RevId: 603756994

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

@@ -61,6 +61,11 @@ protected String actualCustomStringRepresentation() {
     return String.valueOf(actualList);
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(intStreams()).that(stream)....}. Now, you can perform assertions
+   * like that without the {@code about(...)} call.
+   */
   public static Factory<IntStreamSubject, IntStream> intStreams() {
     return IntStreamSubject::new;
   }

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

@@ -61,6 +61,11 @@ protected String actualCustomStringRepresentation() {
     return String.valueOf(actualList);
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(longStreams()).that(stream)....}. Now, you can perform assertions
+   * like that without the {@code about(...)} call.
+   */
   public static Factory<LongStreamSubject, LongStream> longStreams() {
     return LongStreamSubject::new;
   }

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

@@ -81,6 +81,11 @@ public void hasValue(double expected) {
     }
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(optionalDoubles()).that(optional)....}. Now, you can perform
+   * assertions like that without the {@code about(...)} call.
+   */
   public static Subject.Factory<OptionalDoubleSubject, OptionalDouble> optionalDoubles() {
     return (metadata, subject) -> new OptionalDoubleSubject(metadata, subject, "optionalDouble");
   }

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

@@ -74,6 +74,11 @@ public void hasValue(int expected) {
     }
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(optionalInts()).that(optional)....}. Now, you can perform
+   * assertions like that without the {@code about(...)} call.
+   */
   public static Subject.Factory<OptionalIntSubject, OptionalInt> optionalInts() {
     return (metadata, subject) -> new OptionalIntSubject(metadata, subject, "optionalInt");
   }

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

@@ -74,6 +74,11 @@ public void hasValue(long expected) {
     }
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(optionalLongs()).that(optional)....}. Now, you can perform
+   * assertions like that without the {@code about(...)} call.
+   */
   public static Subject.Factory<OptionalLongSubject, OptionalLong> optionalLongs() {
     return (metadata, subject) -> new OptionalLongSubject(metadata, subject, "optionalLong");
   }

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

@@ -84,6 +84,11 @@ public void hasValue(@Nullable Object expected) {
     }
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(paths()).that(path)....}. Now, you can perform assertions like
+   * that without the {@code about(...)} call.
+   */
   public static Subject.Factory<OptionalSubject, Optional<?>> optionals() {
     return (metadata, subject) -> new OptionalSubject(metadata, subject, "optional");
   }

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

@@ -32,6 +32,11 @@ public final class PathSubject extends Subject {
     super(failureMetadata, actual);
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(intStreams()).that(stream)....}. Now, you can perform assertions
+   * like that without the {@code about(...)} call.
+   */
   public static Subject.Factory<PathSubject, Path> paths() {
     return PathSubject::new;
   }

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

@@ -88,6 +88,11 @@ protected String actualCustomStringRepresentation() {
     return String.valueOf(asList);
   }
 
+  /**
+   * Obsolete factory instance. This factory was previously necessary for assertions like {@code
+   * assertWithMessage(...).about(streams()).that(stream)....}. Now, you can perform assertions like
+   * that without the {@code about(...)} call.
+   */
   public static Subject.Factory<StreamSubject, Stream<?>> streams() {
     return StreamSubject::new;
   }

core/src/main/java/com/google/common/truth/Truth8.java

@@ -30,19 +30,12 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
- * The primary entry point for assertions about Java 8 types.
+ * The obsolete entry point for assertions about Java 8 types.
  *
- * <p>To use {@link Truth#assertWithMessage} with a Java 8 type, use {@code
- * assertWithMessage(...).about(}{@link OptionalSubject#optionals optionals()}{@code ).that(...)}
- * (or similarly for the other types).
- *
- * <p>Likewise, to use different failure strategies like {@link Expect}, use {@code
- * expect.about(}{@link OptionalSubject#optionals optionals()}{@code ).that(...)}.
- *
- * <p>For more information about combining different messages, failure strategies, and subjects, see
- * <a href="https://truth.dev/faq#full-chain">How do I specify a custom message/failure
- * behavior/{@code Subject} type?</a> in the Truth FAQ.
+ * @deprecated Instead of this class's methods, use the identical methods declared in the main
+ *     {@link Truth} class.
  */
+@Deprecated
 // The methods here are no more dangerous that wherever the user got the (e.g.) Stream.
 @SuppressWarnings("Java7ApiChecker")
 public final class Truth8 {
@@ -75,10 +68,6 @@ public static LongStreamSubject assertThat(@Nullable LongStream target) {
     return assertAbout(LongStreamSubject.longStreams()).that(target);
   }
 
-  // TODO(b/64757353): Add support for DoubleStream?
-
-  // Not actually a Java 8 feature, but for now this is the best option since core Truth still has
-  // to support Java environments without java.nio.file such as Android and J2CL.
   @GwtIncompatible
   @J2ObjCIncompatible
   @J2ktIncompatible