Add the 'compile' goal for 'compile-java9'

[cushon]

and update to a newer version of bnd for multi-release jar support, see bndtools/bnd#2227.

[cushon]

@sgammon does this look reasonable to you?

Without this change I'm not seeing the compile-java9 step added in 0e95364 get executed, and the META-INF/versions/9/ classes aren't ending up in the artifact.

[cushon]

Hmm, the version of bnd that supports mr-jars requires JDK 17:

Error:  Failed to execute goal biz.aQute.bnd:bnd-maven-plugin:7.0.0:bnd-process (generate-OSGi-manifest) on project error_prone_parent: Execution generate-OSGi-manifest of goal biz.aQute.bnd:bnd-maven-plugin:7.0.0:bnd-process failed: Unable to load the mojo 'bnd-process' in the plugin 'biz.aQute.bnd:bnd-maven-plugin:7.0.0' due to an API incompatibility: org.codehaus.plexus.component.repository.exception.ComponentLookupException: aQute/bnd/maven/plugin/BndMavenPlugin has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0

[sgammon]

@cushon Whoops! I can't believe that wasn't running. I thought I verified the JAR output. I'll check locally with this change applied and verify it with Guava downstream.

Re/BND, the MRJAR is assembled by the JAR step, and BND tools isn't aware of it. I don't think it needs to be aware of it. There are BND directives for generating module-info.java, but we have a definition so we don't need to generate one.

As far as BND loading MRJARs, I know that support is lacking there too, but the classes under META-INF/versions should be identical anyway and only consist of module-info.class.

[sgammon]

@cushon Adding this directive to the BND tools fixes the build issue with classes in the MRJAR root:

-fixupmessages: ^Classes found in the wrong directory: .*

The final block in root pom.xml is:

              <bnd><![CDATA[
                Bundle-SymbolicName: com.google.$<replacestring;$<replacestring;${project.artifactId};^error_prone;errorprone>;_;.>
                Automatic-Module-Name: $<Bundle-SymbolicName>
                -exportcontents: com.google.errorprone*
                -noextraheaders: true
                -removeheaders: Private-Package
                -fixupmessages: ^Classes found in the wrong directory: .*
              ]]></bnd>

I'm just starting my day, so I'll be around. If you want me to push a PR to fix this let me know

[anthonyvdotbe]

@cushon While you're at it, please remove requires java.base; from module-info.java. Every module requires java.base. Specifying it is like specifying import java.lang.*;.

[sgammon]

@cushon A quick patch, I've verified it includes the classes and only the module-info.class (trying to prevent duplication of the actual classes)

diff --git a/annotations/pom.xml b/annotations/pom.xml
index 39a0627585..e68d412cbc 100644
--- a/annotations/pom.xml
+++ b/annotations/pom.xml
@@ -64,6 +64,9 @@
           </execution>
           <execution>
             <id>compile-java9</id>
+            <goals>
+              <goal>compile</goal>
+            </goals>
             <configuration>
               <source>9</source>
               <target>9</target>
@@ -82,6 +85,9 @@
               <Multi-Release>true</Multi-Release>
             </manifestEntries>
           </archive>
+          <excludes>
+            <exclude>/META-INF/versions/9/com/**/*.class</exclude>
+          </excludes>
         </configuration>
       </plugin>
     </plugins>
diff --git a/pom.xml b/pom.xml
index f7cad3c75b..7c0fc99120 100644
--- a/pom.xml
+++ b/pom.xml
@@ -153,6 +153,7 @@
                 -exportcontents: com.google.errorprone*
                 -noextraheaders: true
                 -removeheaders: Private-Package
+                -fixupmessages: ^Classes found in the wrong directory: .*
               ]]></bnd>
             </configuration>
           </execution>

[sgammon]

@anthonyvdotbe I was under the impression that all Java modules had to depend on java.base? That's why it's there. Is that not the case?

[sgammon]

I'm seeing the JDK 11 failure @cushon. I think I have a fix for that too.

[sgammon]

Okay. Thank you @anthonyvdotbe, I learned something today.

The java.base module is not required to be stated in module-info.java. The JDK 11 failure happens because BND tries to load those classes, but we can make them inert instead:

This patch

• Removes java.base
• Fixes compile goal
• Excludes Java 9 classes but includes module-info.class
• Excludes META-INF from BND (see !META-INF...)
• Applies the fixupmessages to BND

diff --git a/annotations/pom.xml b/annotations/pom.xml
index 39a0627585..e68d412cbc 100644
--- a/annotations/pom.xml
+++ b/annotations/pom.xml
@@ -64,6 +64,9 @@
           </execution>
           <execution>
             <id>compile-java9</id>
+            <goals>
+              <goal>compile</goal>
+            </goals>
             <configuration>
               <source>9</source>
               <target>9</target>
@@ -82,6 +85,9 @@
               <Multi-Release>true</Multi-Release>
             </manifestEntries>
           </archive>
+          <excludes>
+            <exclude>/META-INF/versions/9/com/**/*.class</exclude>
+          </excludes>
         </configuration>
       </plugin>
     </plugins>
diff --git a/annotations/src/main/java/module-info.java b/annotations/src/main/java/module-info.java
index 72215b7677..4c9077dd52 100644
--- a/annotations/src/main/java/module-info.java
+++ b/annotations/src/main/java/module-info.java
@@ -15,7 +15,6 @@
  */
 
 open module com.google.errorprone.annotation {
-  requires java.base;
   requires java.compiler;
   exports com.google.errorprone.annotations;
   exports com.google.errorprone.annotations.concurrent;
diff --git a/pom.xml b/pom.xml
index f7cad3c75b..3dc704b4f8 100644
--- a/pom.xml
+++ b/pom.xml
@@ -150,9 +150,10 @@
               <bnd><![CDATA[
                 Bundle-SymbolicName: com.google.$<replacestring;$<replacestring;${project.artifactId};^error_prone;errorprone>;_;.>
                 Automatic-Module-Name: $<Bundle-SymbolicName>
-                -exportcontents: com.google.errorprone*
+                -exportcontents: com.google.errorprone*,!META-INF.*
                 -noextraheaders: true
                 -removeheaders: Private-Package
+                -fixupmessages: ^Classes found in the wrong directory: .*
               ]]></bnd>
             </configuration>
           </execution>

cc / @cushon

[cushon]

Thanks @sgammon! I pushed another commit that includes the additional changes.