Change <? extends @nullable Object> back to <?>.

(i.e., roll back the com.google.common part of cl/377083162)

The two should be equivalent, but Kotlin has/had a bug with `<?>` in the context of `@ElementTypesAreNonnullByDefault` (and/or `@ParametersAreNonnullByDefault`?).

Now that we're moving away from `@*AreNonnullByDefault` and onto `@NullMarked`, we can use the simpler version.

This is the next step toward [using JSpecify in Guava](jspecify/jspecify#239 (comment)).

PiperOrigin-RevId: 708605353

android/guava/src/com/google/common/base/Joiner.java

@@ -86,19 +86,12 @@ private Joiner(Joiner prototype) {
     this.separator = prototype.separator;
   }
 
-  /*
-   * In this file, we use <? extends @Nullable Object> instead of <?> to work around a Kotlin bug
-   * (see b/189937072 until we file a bug against Kotlin itself). (The two should be equivalent, so
-   * we normally prefer the shorter one.)
-   */
-
   /**
    * Appends the string representation of each of {@code parts}, using the previously configured
    * separator between each, to {@code appendable}.
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterable<? extends @Nullable Object> parts)
-      throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws IOException {
     return appendTo(appendable, parts.iterator());
   }
 
@@ -109,8 +102,7 @@ public <A extends Appendable> A appendTo(A appendable, Iterable<? extends @Nulla
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterator<? extends @Nullable Object> parts)
-      throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
     checkNotNull(appendable);
     if (parts.hasNext()) {
       appendable.append(toString(parts.next()));
@@ -151,8 +143,7 @@ public final <A extends Appendable> A appendTo(
    * Iterable)}, except that it does not throw {@link IOException}.
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(
-      StringBuilder builder, Iterable<? extends @Nullable Object> parts) {
+  public final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) {
     return appendTo(builder, parts.iterator());
   }
 
@@ -164,8 +155,7 @@ public final StringBuilder appendTo(
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(
-      StringBuilder builder, Iterator<? extends @Nullable Object> parts) {
+  public final StringBuilder appendTo(StringBuilder builder, Iterator<?> parts) {
     try {
       appendTo((Appendable) builder, parts);
     } catch (IOException impossible) {
@@ -204,7 +194,7 @@ public final StringBuilder appendTo(
    * Returns a string containing the string representation of each of {@code parts}, using the
    * previously configured separator between each.
    */
-  public String join(Iterable<? extends @Nullable Object> parts) {
+  public String join(Iterable<?> parts) {
     // We don't use the same optimization here as in the JRE flavor.
     // TODO: b/381289911 - Evaluate the performance impact of doing so.
     return join(parts.iterator());
@@ -224,7 +214,7 @@ public String join(Iterable<? extends @Nullable Object> parts) {
    *
    * @since 11.0
    */
-  public final String join(Iterator<? extends @Nullable Object> parts) {
+  public final String join(Iterator<?> parts) {
     return appendTo(new StringBuilder(), parts).toString();
   }
 
@@ -284,8 +274,7 @@ public String join(Iterable<? extends @Nullable Object> parts) {
       }
 
       @Override
-      public <A extends Appendable> A appendTo(
-          A appendable, Iterator<? extends @Nullable Object> parts) throws IOException {
+      public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
         checkNotNull(appendable, "appendable");
         checkNotNull(parts, "parts");
         while (parts.hasNext()) {

guava/src/com/google/common/base/Joiner.java

@@ -86,19 +86,12 @@ private Joiner(Joiner prototype) {
     this.separator = prototype.separator;
   }
 
-  /*
-   * In this file, we use <? extends @Nullable Object> instead of <?> to work around a Kotlin bug
-   * (see b/189937072 until we file a bug against Kotlin itself). (The two should be equivalent, so
-   * we normally prefer the shorter one.)
-   */
-
   /**
    * Appends the string representation of each of {@code parts}, using the previously configured
    * separator between each, to {@code appendable}.
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterable<? extends @Nullable Object> parts)
-      throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws IOException {
     return appendTo(appendable, parts.iterator());
   }
 
@@ -109,8 +102,7 @@ public <A extends Appendable> A appendTo(A appendable, Iterable<? extends @Nulla
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterator<? extends @Nullable Object> parts)
-      throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
     checkNotNull(appendable);
     if (parts.hasNext()) {
       appendable.append(toString(parts.next()));
@@ -151,8 +143,7 @@ public final <A extends Appendable> A appendTo(
    * Iterable)}, except that it does not throw {@link IOException}.
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(
-      StringBuilder builder, Iterable<? extends @Nullable Object> parts) {
+  public final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) {
     return appendTo(builder, parts.iterator());
   }
 
@@ -164,8 +155,7 @@ public final StringBuilder appendTo(
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(
-      StringBuilder builder, Iterator<? extends @Nullable Object> parts) {
+  public final StringBuilder appendTo(StringBuilder builder, Iterator<?> parts) {
     try {
       appendTo((Appendable) builder, parts);
     } catch (IOException impossible) {
@@ -204,7 +194,7 @@ public final StringBuilder appendTo(
    * Returns a string containing the string representation of each of {@code parts}, using the
    * previously configured separator between each.
    */
-  public String join(Iterable<? extends @Nullable Object> parts) {
+  public String join(Iterable<?> parts) {
     /*
      * If we can quickly determine how many elements there are likely to be, then we can use the
      * fastest possible implementation, which delegates to the array overload of String.join.
@@ -264,7 +254,7 @@ public String join(Iterable<? extends @Nullable Object> parts) {
    *
    * @since 11.0
    */
-  public final String join(Iterator<? extends @Nullable Object> parts) {
+  public final String join(Iterator<?> parts) {
     return appendTo(new StringBuilder(), parts).toString();
   }
 
@@ -324,8 +314,7 @@ public String join(Iterable<? extends @Nullable Object> parts) {
       }
 
       @Override
-      public <A extends Appendable> A appendTo(
-          A appendable, Iterator<? extends @Nullable Object> parts) throws IOException {
+      public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
         checkNotNull(appendable, "appendable");
         checkNotNull(parts, "parts");
         while (parts.hasNext()) {