code: public Set<JavaFileObject> getFileObjects() {
          if (fileObjects == null) {
              fileObjects = new LinkedHashSet<>();
          }
          if (files != null) {
              JavacFileManager jfm = (JavacFileManager) getFileManager();
              for (JavaFileObject fo: jfm.getJavaFileObjectsFromPaths(files))
                  fileObjects.add(fo);
          }
          return fileObjects;
      }
docs: Gets the files to be compiled.
  @return the files to be compiled