Don't put two copies of every class into the Guava jar.

We need to compile Guava twice:
- once to build the actual classes with `-source 8` (to maintain Java 8 compatibility)
- once to build `module-info`, which requires `-source 9` and thus is incompatible with the "main" build

I had been under the mistaken impression that the latter compile still needed to pass all the sources. As a result, we had the second compile build `module-info` _and_ all the classes. We then had configuration in `maven-jar-plugin` to ignore the other classes.

But the `maven-jar-plugin` configuration doesn't help because we're using `maven-bundle-plugin` instead, at least for the `guava` itself. (I didn't look into `guava-testlib`, `guava-gwt`, or the tests of any module, though note that (IIRC) the only other one that's modularized (and thus might benefit from our module-related `maven-jar-plugin` configuration) is `guava-testlib`.)

Luckily, it turns out that we _can_ compile `module-info` by itself. So now the build does that.

(Also, bump `maven-jar-plugin` while in the area.)

See #6614 (comment)

RELNOTES=Removed the extra copy of each class from the Guava jar. The extra copies were an accidental addition from the modularization work in [Guava 33.4.5](https://github.com/google/guava/releases/tag/v33.4.5).
PiperOrigin-RevId: 740019355

Author: cpovirk

android/guava/pom.xml

@@ -119,6 +119,9 @@
               <compileSourceRoots>
                 <compileSourceRoot>${project.basedir}/src</compileSourceRoot>
               </compileSourceRoots>
+              <includes>
+                <include>module-info.java</include>
+              </includes>
 
               <!--
                 JPMS needs access to the module sources to complete a modular Java build. We also need to override the

android/pom.xml

@@ -233,8 +233,9 @@
         </plugin>
         <plugin>
           <artifactId>maven-jar-plugin</artifactId>
-          <version>3.4.0</version>
+          <version>3.4.2</version>
           <configuration>
+            <!-- Warning: Guava (at least the main module) uses maven-bundle-plugin, not maven-jar-plugin, so the configuration does not apply to it. That configuration may or may not apply to guava-testlib or other modules. -->
             <excludes>
               <!-- The root module (where applicable) is withheld because it is provided at `META-INF/versions/9/`. -->
               <exclude>/module-info.class</exclude>

guava/pom.xml

@@ -119,6 +119,9 @@
               <compileSourceRoots>
                 <compileSourceRoot>${project.basedir}/src</compileSourceRoot>
               </compileSourceRoots>
+              <includes>
+                <include>module-info.java</include>
+              </includes>
 
               <!--
                 JPMS needs access to the module sources to complete a modular Java build. We also need to override the

pom.xml

@@ -234,8 +234,9 @@
         </plugin>
         <plugin>
           <artifactId>maven-jar-plugin</artifactId>
-          <version>3.4.0</version>
+          <version>3.4.2</version>
           <configuration>
+            <!-- Warning: Guava (at least the main module) uses maven-bundle-plugin, not maven-jar-plugin, so the configuration does not apply to it. That configuration may or may not apply to guava-testlib or other modules. -->
             <excludes>
               <!-- The root module (where applicable) is withheld because it is provided at `META-INF/versions/9/`. -->
               <exclude>/module-info.class</exclude>