fix: Compilation issues with error-prone on JDK16+ (#100)

See: https://errorprone.info/docs/installation

Author: nielm

pom.xml

@@ -115,10 +115,22 @@
         <configuration>
           <showWarnings>true</showWarnings>
           <failOnWarning>true</failOnWarning>
+          <fork>true</fork>
           <compilerArgs>
             <arg>-Xlint:-options</arg>
             <arg>-XDcompilePolicy=simple</arg>
             <arg>-Xplugin:ErrorProne -XepExcludedPaths:${project.build.directory}/generated-sources/.* -XepDisableWarningsInGeneratedCode</arg>
+            <!-- Required for ERROR-PRONE on JDK 16+ See https://errorprone.info/docs/installation -->
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED</arg>
+            <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED</arg>
+            <arg>-J--add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED</arg>
+            <arg>-J--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED</arg>
           </compilerArgs>
           <annotationProcessorPaths>
             <path>