[RELEASE-FIX] Fix unittests on jdk 17 (#7)

Newer dependency should not result in errors like `cannot access class com.sun.tools.javac.api.JavacTool`
Also required to add some JVM flags for tests, as the dependency alone is not enough.
Inspired by google/compile-testing@e794c75

pom.xml

@@ -70,7 +70,7 @@
  <junit.version>5.1.0</junit.version>
  <junit-platform.version>1.1.0</junit-platform.version>
  <opentest4j.version>1.0.0</opentest4j.version>
- <testing-compile.version>0.19</testing-compile.version>
+ <testing-compile.version>0.21.0</testing-compile.version>
  <maven.surefire.plugin.version>2.19</maven.surefire.plugin.version>
 
  <maven.compiler.source>1.8</maven.compiler.source>
@@ -327,6 +327,19 @@
  </plugins>
  </build>
  </profile>
+ <profile>
+ <id>add-exports</id>
+ <activation>
+ <jdk>[9,)</jdk>
+ </activation>
+ <properties>
+ <test.jvm.flags>
+ --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+ --add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+ --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+ </test.jvm.flags>
+ </properties>
+ </profile>
  </profiles>
 
 </project>

processors/pom.xml

@@ -98,6 +98,9 @@
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
+ <configuration>
+ <argLine>${test.jvm.flags}</argLine>
+ </configuration>
  </plugin>
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>