public Path getRelativeSourceFilePath() {
        return relativeSourceFilePath;
    }
Simple struct to keep track of relative path of source file (
original binary file, e.g. /subdir/document1.doc)
and the extract file (e.g. /subdir/document1.doc.json).
tika-eval/tika-eval-app/src/main/java/org/apache/tika/eval/app/EvalFilePaths.java