Bump docs and compatibility checking for API Level 24.

This initial CL doesn't take advantage of that by changing `guava-android` to expose more APIs that use types `Function` or `Stream`. That said, we have already been exposing _some_ such APIs for a while now. We are likely to expose more in the future.

This `minSdkVersion` bump follows [other Google foundational libraries](https://issuetracker.google.com/issues/474169350), and we expect the bump itself to have no practical impact on users.

RELNOTES=Our Android `minSdkVersion` is now 24 (Nougat). This follows the minimum of Google's foundational Android libraries, and we expect it to have no practical impact on users.
PiperOrigin-RevId: 953524131

Author: cpovirk

README.md

@@ -127,8 +127,7 @@ class by appending the class name to guava.dev. For example,
 6.  For the mainline flavor, we test the libraries using a range of OpenJDK
     versions on Linux and Windows. Some features, especially in
     `com.google.common.io`, may not work correctly in non-Linux environments.
-    For the Android flavor, our unit tests also run on API level 23
-    (Marshmallow).
+    For the Android flavor, our unit tests also run on API level 24 (Nougat).
 
 [guava-snapshot-api-docs]: https://guava.dev/releases/snapshot-jre/api/docs/
 [guava-snapshot-api-diffs]: https://guava.dev/releases/snapshot-jre/api/diffs/

android/guava/src/com/google/common/util/concurrent/Runnables.java

@@ -24,8 +24,8 @@
 @GwtCompatible
 public final class Runnables {
   /*
-   * If we inline this, it's not longer a singleton under Android (at least under the Marshmallow
-   * version that we're testing under) or J2CL.
+   * If we inline this, it's no longer a singleton under Android (at least as recently as Android 17)
+   * or J2CL.
    *
    * That's not necessarily a real-world problem, but it does break our tests.
    */

android/pom.xml

@@ -63,7 +63,7 @@
     <error_prone_core.version>2.50.0</error_prone_core.version>
     <exec-maven-plugin.version>3.5.0</exec-maven-plugin.version>
     <failureaccess.version>1.0.3</failureaccess.version>
-    <gummy-bears-api-23-version>0.12.0</gummy-bears-api-23-version>
+    <gummy-bears-api-24-version>0.15.0</gummy-bears-api-24-version>
     <gwt-maven-plugin.version>1.1.0</gwt-maven-plugin.version>
     <gwt.version>2.13.0</gwt.version>
     <j2objc.version>3.1</j2objc.version>
@@ -435,8 +435,8 @@
             <checkTestClasses>true</checkTestClasses>
             <signature>
               <groupId>com.toasttab.android</groupId>
-              <artifactId>gummy-bears-api-23</artifactId>
-              <version>${gummy-bears-api-23-version}</version>
+              <artifactId>gummy-bears-api-24</artifactId>
+              <version>${gummy-bears-api-24-version}</version>
             </signature>
             <ignores>
               <!-- Unsafe isn't part of the documented Android API, but it is available.

guava/src/com/google/common/util/concurrent/Runnables.java

@@ -24,8 +24,8 @@
 @GwtCompatible
 public final class Runnables {
   /*
-   * If we inline this, it's not longer a singleton under Android (at least under the Marshmallow
-   * version that we're testing under) or J2CL.
+   * If we inline this, it's no longer a singleton under Android (at least as recently as Android 17)
+   * or J2CL.
    *
    * That's not necessarily a real-world problem, but it does break our tests.
    */

pom.xml

@@ -64,7 +64,7 @@
     <error_prone_core.version>2.50.0</error_prone_core.version>
     <exec-maven-plugin.version>3.5.0</exec-maven-plugin.version>
     <failureaccess.version>1.0.3</failureaccess.version>
-    <gummy-bears-api-23-version>0.12.0</gummy-bears-api-23-version>
+    <gummy-bears-api-24-version>0.15.0</gummy-bears-api-24-version>
     <gwt-maven-plugin.version>1.1.0</gwt-maven-plugin.version>
     <gwt.version>2.13.0</gwt.version>
     <j2objc.version>3.1</j2objc.version>