docs: public Nullness getNullness(TreePath exprPath, Context context) {
      try {
        nullnessPropagation.setContext(context).setCompilationUnit(exprPath.getCompilationUnit());
        return DataFlow.expressionDataflow(exprPath, context, nullnessPropagation);
      } finally {
        nullnessPropagation.setContext(null).setCompilationUnit(null);
      }
    }