context: add the four-value withValues(). (#2506)

context/src/main/java/io/grpc/Context.java

@@ -330,6 +330,15 @@ public class Context {
     return new Context(this, new Object[][]{{k1, v1}, {k2, v2}, {k3, v3}});
   }
 
+  /**
+   * Create a new context with the given key value set. The new context will cascade cancellation
+   * from its parent.
+   */
+  public <V1, V2, V3, V4> Context withValues(Key<V1> k1, V1 v1, Key<V2> k2, V2 v2,
+      Key<V3> k3, V3 v3, Key<V4> k4, V4 v4) {
+    return new Context(this, new Object[][]{{k1, v1}, {k2, v2}, {k3, v3}, {k4, v4}});
+  }
+
   /**
    * Create a new context which propagates the values of this context but does not cascade its
    * cancellation.

context/src/test/java/io/grpc/ContextTest.java

@@ -78,6 +78,7 @@ public class ContextTest {
   private static final Context.Key<String> FOOD = Context.keyWithDefault("food", "lasagna");
   private static final Context.Key<String> COLOR = Context.key("color");
   private static final Context.Key<Object> FAVORITE = Context.key("favorite");
+  private static final Context.Key<Integer> LUCKY = Context.key("lucky");
 
   private Context listenerNotifedContext;
   private CountDownLatch deadlineLatch = new CountDownLatch(1);
@@ -246,6 +247,23 @@ public class ContextTest {
     base.attach();
   }
 
+  @Test
+  public void withValuesFour() {
+    Object fav = new Object();
+    Context base = Context.current().withValues(PET, "dog", COLOR, "blue");
+    Context child = base.withValues(PET, "cat", FOOD, "cheese", FAVORITE, fav, LUCKY, 7);
+
+    child.attach();
+
+    assertEquals("cat", PET.get());
+    assertEquals("cheese", FOOD.get());
+    assertEquals("blue", COLOR.get());
+    assertEquals(fav, FAVORITE.get());
+    assertEquals(7, (int) LUCKY.get());
+
+    base.attach();
+  }
+
   @Test
   public void cancelReturnsFalseIfAlreadyCancelled() {
     Context.CancellableContext base = Context.current().withCancellation();