[Java] Add doc for Ray.get api that throws an exception if it times out (#23666)

Add doc for Ray.get api that throws an exception if it times out

![image](https://user-images.githubusercontent.com/11072802/161364231-4337124d-3141-4334-879c-f88cecc0d818.png)

Co-authored-by: 稚鱼 <lianjunwen.ljw@antgroup.com>

java/api/src/main/java/io/ray/api/ObjectRef.java

@@ -18,6 +18,7 @@ public interface ObjectRef<T> {
    * available.
    *
    * @param timeoutMs The maximum amount of time in miliseconds to wait before returning.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   T get(long timeoutMs);
 }

java/api/src/main/java/io/ray/api/Ray.java

@@ -83,6 +83,7 @@ public final class Ray extends RayCall {
    * @param objectRef The reference of the object to get.
    * @param timeoutMs The maximum amount of time in miliseconds to wait before returning.
    * @return The Java object.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   public static <T> T get(ObjectRef<T> objectRef, long timeoutMs) {
     return internal().get(objectRef, timeoutMs);
@@ -104,6 +105,7 @@ public final class Ray extends RayCall {
    * @param objectList A list of object references.
    * @param timeoutMs The maximum amount of time in miliseconds to wait before returning.
    * @return A list of Java objects.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   public static <T> List<T> get(List<ObjectRef<T>> objectList, long timeoutMs) {
     return internal().get(objectList, timeoutMs);

java/api/src/main/java/io/ray/api/runtime/RayRuntime.java

@@ -74,6 +74,7 @@ public interface RayRuntime {
    * @param objectRef The reference of the object to get.
    * @param timeoutMs The maximum amount of time in millseconds to wait before returning.
    * @return The Java object.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   <T> T get(ObjectRef<T> objectRef, long timeoutMs);
 
@@ -83,6 +84,7 @@ public interface RayRuntime {
    * @param objectRefs The list of object references.
    * @param timeoutMs The maximum amount of time in millseconds to wait before returning.
    * @return A list of Java objects.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   <T> List<T> get(List<ObjectRef<T>> objectRefs, long timeoutMs);
 

java/runtime/src/main/java/io/ray/runtime/object/ObjectStore.java

@@ -102,6 +102,7 @@ public abstract class ObjectStore {
    * @param objectIds IDs of the objects to get.
    * @param timeoutMs Timeout in milliseconds, wait infinitely if it's negative.
    * @return Result list of objects data.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   public abstract List<NativeRayObject> getRaw(List<ObjectId> objectIds, long timeoutMs);
 
@@ -124,6 +125,7 @@ public abstract class ObjectStore {
    * @param <T> Type of these objects.
    * @param timeoutMs The maximum amount of time in seconds to wait before returning.
    * @return A list of GetResult objects.
+   * @throws RayTimeoutException If it's timeout to get the object.
    */
   @SuppressWarnings("unchecked")
   public <T> List<T> get(List<ObjectId> ids, Class<?> elementType, long timeoutMs) {