[MCOMPILER-333] Cleanup generated source files (#214)

Signed-off-by: Jorge Solórzano <jorsol@gmail.com>

Author: jorsol

src/main/java/org/apache/maven/plugin/compiler/AbstractCompilerMojo.java

@@ -30,6 +30,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -41,6 +42,7 @@
 import java.util.Properties;
 import java.util.Set;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.apache.maven.RepositoryUtils;
 import org.apache.maven.artifact.handler.ArtifactHandler;
@@ -1173,6 +1175,17 @@ public void execute() throws MojoExecutionException, CompilationFailureException
         if (useIncrementalCompilation) {
             incrementalBuildHelperRequest.outputDirectory(getOutputDirectory());
 
+            // Cleanup the generated source files created by annotation processing
+            // they are regenerated by the java compiler.
+            if (getGeneratedSourcesDirectory() != null) {
+                try (Stream<Path> walk =
+                        Files.walk(getGeneratedSourcesDirectory().toPath())) {
+                    walk.sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(File::delete);
+                } catch (IOException ex) {
+                    getLog().warn("I/O error deleting the annotation processing generated files: " + ex.getMessage());
+                }
+            }
+
             incrementalBuildHelper.beforeRebuildExecution(incrementalBuildHelperRequest);
 
             getLog().debug("incrementalBuildHelper#beforeRebuildExecution");