Initial multi-release jar support

Signed-off-by: Ryan Nett <JNett96@gmail.com>

Author: rnett

tensorflow-core/tensorflow-core-api/pom.xml

@@ -22,6 +22,9 @@
     <java.module.name>org.tensorflow.core.api</java.module.name>
     <ndarray.version>0.3.1</ndarray.version>
     <truth.version>1.0.1</truth.version>
+
+    <java9.sourceDirectory>${project.basedir}/src/main/java9</java9.sourceDirectory>
+    <java9.build.outputDirectory>${project.build.directory}/classes-java9</java9.build.outputDirectory>
   </properties>
 
   <dependencies>
@@ -143,6 +146,50 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-antrun-plugin</artifactId>
+        <version>3.0.0</version>
+        <executions>
+          <execution>
+            <id>compile-java9</id>
+            <phase>compile</phase>
+            <configuration>
+              <target>
+                <mkdir dir="${java9.build.outputDirectory}" />
+                <javac srcdir="${java9.sourceDirectory}" destdir="${java9.build.outputDirectory}"
+                  classpath="${project.build.outputDirectory}" includeantruntime="false"
+                  target="9" source="9" release="9"/>
+              </target>
+            </configuration>
+            <goals>
+              <goal>run</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-resources-plugin</artifactId>
+        <version>3.2.0</version>
+        <executions>
+          <execution>
+            <id>copy-resources</id>
+            <phase>prepare-package</phase>
+            <goals>
+              <goal>copy-resources</goal>
+            </goals>
+            <configuration>
+              <outputDirectory>${project.build.outputDirectory}/META-INF/versions/9</outputDirectory>
+              <resources>
+                <resource>
+                  <directory>${java9.build.outputDirectory}</directory>
+                </resource>
+              </resources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.0</version>
@@ -372,6 +419,7 @@
           <archive>
             <manifestEntries>
               <Automatic-Module-Name>${java.module.name}</Automatic-Module-Name>
+              <Multi-Release>true</Multi-Release>
             </manifestEntries>
           </archive>
         </configuration>

tensorflow-core/tensorflow-core-api/src/main/java/org/tensorflow/MRTest.java

@@ -0,0 +1,24 @@
+/*
+ Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+=======================================================================
+
+*/
+package org.tensorflow;
+
+public class MRTest {
+  public static int version() {
+    return 8;
+  }
+}

tensorflow-core/tensorflow-core-api/src/main/java9/org/tensorflow/MRTest.java

@@ -0,0 +1,27 @@
+/*
+  Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ =======================================================================
+
+ */
+package org.tensorflow;
+
+import java.lang.ref.Cleaner;
+
+public class MRTest {
+  public static int version(){
+    Cleaner.create();
+    return 9;
+  }
+}