FileTrees withStub(@NotNull StubTree stub, @Nullable FileElement ast) throws StubTreeLoader.StubTreeAndIndexUnmatchCoarseException {
    assert derefTreeElement() == ast;
    return new FileTrees(myFile, new SoftReference<>(stub), myTreeElementPointer, myRefToPsi)
      .reconcilePsi(stub, ast, false);
  }
FileTrees withStub(@NotNull StubTree stub, @Nullable FileElement ast)