public @Nullable Set<ClassRepr> getClasses(final String sourceFileName) {
    final File f = new File(sourceFileName);
    synchronized (myLock) {
      final Collection<ClassFileRepr> reprs = sourceFileToClassesGet(f);
      if (reprs == null || reprs.isEmpty()) {
        return null;
      }
      final Set<ClassRepr> result = new HashSet<>();
      for (ClassFileRepr repr : reprs) {
        if (repr instanceof ClassRepr) {
          result.add((ClassRepr)repr);
        }
      }
      return result;
    }
  }
public @Nullable Set<ClassRepr> getClasses(final String sourceFileName)