In ForwadingJavaFileObject.java there are many imports which are not used.
Out of "import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.Reader; import java.io.Writer; import java.net.URI;
 import javax.lang.model.element.Modifier; import javax.lang.model.element.NestingKind;
Only
javax.lang.model.element.Modifier; javax.lang.model.element.NestingKind; are used in the source file. Rest can be deleted.