Discourage Function.identity().

cpovirk · Google Java Core Libraries · commit c5255f16a593 · 2023-06-27T12:38:50.000-07:00
RELNOTES=n/a
PiperOrigin-RevId: 543821637
diff --git a/android/guava/src/com/google/common/base/Functions.java b/android/guava/src/com/google/common/base/Functions.java
@@ -79,7 +79,12 @@ public String toString() {
     }
   }
 
-  /** Returns the identity function. */
+  /**
+   * Returns the identity function.
+   *
+   * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often
+   * more readable.
+   */
   // implementation is "fully variant"; E has become a "pass-through" type
   @SuppressWarnings("unchecked")
   public static <E extends @Nullable Object> Function<E, E> identity() {
diff --git a/guava/src/com/google/common/base/Functions.java b/guava/src/com/google/common/base/Functions.java
@@ -79,7 +79,12 @@ public String toString() {
     }
   }
 
-  /** Returns the identity function. */
+  /**
+   * Returns the identity function.
+   *
+   * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often
+   * more readable.
+   */
   // implementation is "fully variant"; E has become a "pass-through" type
   @SuppressWarnings("unchecked")
   public static <E extends @Nullable Object> Function<E, E> identity() {

Original file line number	Diff line number	Diff line change
`@@ -79,7 +79,12 @@ public String toString() {`
`79`	`79`	`}`
`80`	`80`	`}`
`81`	`81`
`82`		`- /** Returns the identity function. */`
	`82`	`+ /**`
	`83`	`+ * Returns the identity function.`
	`84`	`+ *`
	`85`	`+ * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often`
	`86`	`+ * more readable.`
	`87`	`+ */`
`83`	`88`	`// implementation is "fully variant"; E has become a "pass-through" type`
`84`	`89`	`@SuppressWarnings("unchecked")`
`85`	`90`	`public static <E extends @Nullable Object> Function<E, E> identity() {`