diff --git a/jdk/src/share/classes/java/time/Duration.java b/jdk/src/share/classes/java/time/Duration.java
index 8650cdffecd..4a5220000f6 100644
--- a/jdk/src/share/classes/java/time/Duration.java
+++ b/jdk/src/share/classes/java/time/Duration.java
@@ -118,6 +118,13 @@ import java.util.regex.Pattern;
  * most applications.
  * See {@link Instant} for a discussion as to the meaning of the second and time-scales.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code Duration} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/Instant.java b/jdk/src/share/classes/java/time/Instant.java
index 2f03ff5c5de..d91e1c86568 100644
--- a/jdk/src/share/classes/java/time/Instant.java
+++ b/jdk/src/share/classes/java/time/Instant.java
@@ -197,6 +197,13 @@ import java.util.Objects;
  * This includes {@code Instant}, {@code LocalDate}, {@code LocalTime}, {@code OffsetDateTime},
  * {@code ZonedDateTime} and {@code Duration}.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code Instant} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/LocalDate.java b/jdk/src/share/classes/java/time/LocalDate.java
index 91a2adf0e3a..c8ee89c87c5 100644
--- a/jdk/src/share/classes/java/time/LocalDate.java
+++ b/jdk/src/share/classes/java/time/LocalDate.java
@@ -122,6 +122,13 @@ import java.util.Objects;
  * However, any application that makes use of historical dates, and requires them
  * to be accurate will find the ISO-8601 approach unsuitable.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code LocalDate} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/LocalDateTime.java b/jdk/src/share/classes/java/time/LocalDateTime.java
index f8787a6c25d..f9975d82329 100644
--- a/jdk/src/share/classes/java/time/LocalDateTime.java
+++ b/jdk/src/share/classes/java/time/LocalDateTime.java
@@ -120,6 +120,13 @@ import java.util.Objects;
  * However, any application that makes use of historical dates, and requires them
  * to be accurate will find the ISO-8601 approach unsuitable.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code LocalDateTime} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/LocalTime.java b/jdk/src/share/classes/java/time/LocalTime.java
index a1945c36383..08a06317413 100644
--- a/jdk/src/share/classes/java/time/LocalTime.java
+++ b/jdk/src/share/classes/java/time/LocalTime.java
@@ -110,6 +110,13 @@ import java.util.Objects;
  * in most of the world. This API assumes that all calendar systems use the same
  * representation, this class, for time-of-day.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code LocalTime} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/MonthDay.java b/jdk/src/share/classes/java/time/MonthDay.java
index 6801d296f41..2339cad5397 100644
--- a/jdk/src/share/classes/java/time/MonthDay.java
+++ b/jdk/src/share/classes/java/time/MonthDay.java
@@ -112,6 +112,13 @@ import java.util.Objects;
  * However, any application that makes use of historical dates, and requires them
  * to be accurate will find the ISO-8601 approach unsuitable.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code MonthDay} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/OffsetDateTime.java b/jdk/src/share/classes/java/time/OffsetDateTime.java
index 7c9d7a2106d..caecddca0f4 100644
--- a/jdk/src/share/classes/java/time/OffsetDateTime.java
+++ b/jdk/src/share/classes/java/time/OffsetDateTime.java
@@ -113,6 +113,13 @@ import java.util.Objects;
  * in simpler applications. This class may be used when modeling date-time concepts in
  * more detail, or when communicating to a database or in a network protocol.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code OffsetDateTime} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/OffsetTime.java b/jdk/src/share/classes/java/time/OffsetTime.java
index 621edf162c1..466cf5ae639 100644
--- a/jdk/src/share/classes/java/time/OffsetTime.java
+++ b/jdk/src/share/classes/java/time/OffsetTime.java
@@ -103,6 +103,13 @@ import java.util.Objects;
  * For example, the value "13:45.30.123456789+02:00" can be stored
  * in an {@code OffsetTime}.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code OffsetTime} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/Period.java b/jdk/src/share/classes/java/time/Period.java
index 46238b62943..ff6db0885f0 100644
--- a/jdk/src/share/classes/java/time/Period.java
+++ b/jdk/src/share/classes/java/time/Period.java
@@ -120,6 +120,13 @@ import java.util.regex.Pattern;
  * The period is modeled as a directed amount of time, meaning that individual parts of the
  * period may be negative.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code Period} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/Year.java b/jdk/src/share/classes/java/time/Year.java
index a032c7d4d38..cc68951351b 100644
--- a/jdk/src/share/classes/java/time/Year.java
+++ b/jdk/src/share/classes/java/time/Year.java
@@ -120,6 +120,13 @@ import java.util.Objects;
  * However, any application that makes use of historical dates, and requires them
  * to be accurate will find the ISO-8601 approach unsuitable.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code Year} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/YearMonth.java b/jdk/src/share/classes/java/time/YearMonth.java
index 4a8d257d897..e5f42100ac0 100644
--- a/jdk/src/share/classes/java/time/YearMonth.java
+++ b/jdk/src/share/classes/java/time/YearMonth.java
@@ -116,6 +116,13 @@ import java.util.Objects;
  * However, any application that makes use of historical dates, and requires them
  * to be accurate will find the ISO-8601 approach unsuitable.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code YearMonth} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/ZoneId.java b/jdk/src/share/classes/java/time/ZoneId.java
index 70dd7d1f891..9b8ebc7267a 100644
--- a/jdk/src/share/classes/java/time/ZoneId.java
+++ b/jdk/src/share/classes/java/time/ZoneId.java
@@ -160,6 +160,13 @@ import java.util.TimeZone;
  * This approach is designed to allow a {@link ZonedDateTime} to be loaded and
  * queried, but not modified, on a Java Runtime with incomplete time-zone information.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code ZoneId} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This abstract class has two implementations, both of which are immutable and thread-safe.
  * One implementation models region-based IDs, the other is {@code ZoneOffset} modelling
diff --git a/jdk/src/share/classes/java/time/ZoneOffset.java b/jdk/src/share/classes/java/time/ZoneOffset.java
index 180eac41a27..efbdec9a934 100644
--- a/jdk/src/share/classes/java/time/ZoneOffset.java
+++ b/jdk/src/share/classes/java/time/ZoneOffset.java
@@ -115,6 +115,13 @@ import java.util.concurrent.ConcurrentMap;
  * Implementations may choose to cache certain common offsets, however
  * applications must not rely on such caching.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code ZoneOffset} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/ZonedDateTime.java b/jdk/src/share/classes/java/time/ZonedDateTime.java
index c7e73c45d68..b1342be5e47 100644
--- a/jdk/src/share/classes/java/time/ZonedDateTime.java
+++ b/jdk/src/share/classes/java/time/ZonedDateTime.java
@@ -142,6 +142,13 @@ import java.util.Objects;
  * a vital, but secondary, piece of information, used to ensure that the class
  * represents an instant, especially during a daylight savings overlap.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code ZonedDateTime} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * A {@code ZonedDateTime} holds state equivalent to three separate objects,
  * a {@code LocalDateTime}, a {@code ZoneId} and the resolved {@code ZoneOffset}.
diff --git a/jdk/src/share/classes/java/time/chrono/HijrahDate.java b/jdk/src/share/classes/java/time/chrono/HijrahDate.java
index bbaa8e04de7..9ab791ce8e5 100644
--- a/jdk/src/share/classes/java/time/chrono/HijrahDate.java
+++ b/jdk/src/share/classes/java/time/chrono/HijrahDate.java
@@ -103,6 +103,14 @@ import java.time.temporal.ValueRange;
  * to create new HijrahDate instances.
  * Alternatively, the {@link #withVariant} method can be used to convert
  * to a new HijrahChronology.
+ *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code HijrahDate} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/chrono/JapaneseDate.java b/jdk/src/share/classes/java/time/chrono/JapaneseDate.java
index d68e496bd1c..5c7e545042a 100644
--- a/jdk/src/share/classes/java/time/chrono/JapaneseDate.java
+++ b/jdk/src/share/classes/java/time/chrono/JapaneseDate.java
@@ -111,6 +111,13 @@ import sun.util.calendar.LocalGregorianCalendar;
  * Calling {@code japaneseDate.get(ERA)} will return 2, corresponding to
  * {@code JapaneseChronology.ERA_HEISEI}.<br>
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code JapaneseDate} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/chrono/MinguoDate.java b/jdk/src/share/classes/java/time/chrono/MinguoDate.java
index 0e9de44f463..2cb49b6b600 100644
--- a/jdk/src/share/classes/java/time/chrono/MinguoDate.java
+++ b/jdk/src/share/classes/java/time/chrono/MinguoDate.java
@@ -91,6 +91,13 @@ import java.util.Objects;
  * This calendar system is primarily used in the Republic of China, often known as Taiwan.
  * Dates are aligned such that {@code 0001-01-01 (Minguo)} is {@code 1912-01-01 (ISO)}.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code MinguoDate} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/src/share/classes/java/time/chrono/ThaiBuddhistDate.java b/jdk/src/share/classes/java/time/chrono/ThaiBuddhistDate.java
index ba1e8d24e21..9e8b88d3465 100644
--- a/jdk/src/share/classes/java/time/chrono/ThaiBuddhistDate.java
+++ b/jdk/src/share/classes/java/time/chrono/ThaiBuddhistDate.java
@@ -91,6 +91,13 @@ import java.util.Objects;
  * This calendar system is primarily used in Thailand.
  * Dates are aligned such that {@code 2484-01-01 (Buddhist)} is {@code 1941-01-01 (ISO)}.
  *
+ * <p>
+ * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
+ * class; use of identity-sensitive operations (including reference equality
+ * ({@code ==}), identity hash code, or synchronization) on instances of
+ * {@code ThaiBuddhistDate} may have unpredictable results and should be avoided.
+ * The {@code equals} method should be used for comparisons.
+ *
  * @implSpec
  * This class is immutable and thread-safe.
  *
diff --git a/jdk/test/java/time/tck/java/time/TCKLocalDateTime.java b/jdk/test/java/time/tck/java/time/TCKLocalDateTime.java
index 6303f5acdc0..40ed5347589 100644
--- a/jdk/test/java/time/tck/java/time/TCKLocalDateTime.java
+++ b/jdk/test/java/time/tck/java/time/TCKLocalDateTime.java
@@ -1847,7 +1847,7 @@ public class TCKLocalDateTime extends AbstractDateTimeTest {
             LocalDateTime dt = base.plusMinutes(i);
             t = t.plusMinutes(1);
 
-            if (t == LocalTime.MIDNIGHT) {
+            if (t.equals(LocalTime.MIDNIGHT)) {
                 d = d.plusDays(1);
             }
 
@@ -2539,7 +2539,7 @@ public class TCKLocalDateTime extends AbstractDateTimeTest {
             LocalDateTime dt = base.minusMinutes(i);
             t = t.plusMinutes(1);
 
-            if (t == LocalTime.MIDNIGHT) {
+            if (t.equals(LocalTime.MIDNIGHT)) {
                 d = d.plusDays(1);
             }