RegexTokenizer: Default token arguments are not mapped to vocabulary index
The ID's of the default special tokens in RegexTokenizer  are set here:

https://github.com/NVIDIA/NeMo/blob/72d78d832c6332ccc7f44811fb777eb7044df1d8/nemo/collections/common/tokenizers/regex_tokenizer.py#L75-L82

However, the constructor, allows custom special tokens:

https://github.com/NVIDIA/NeMo/blob/72d78d832c6332ccc7f44811fb777eb7044df1d8/nemo/collections/common/tokenizers/regex_tokenizer.py#L42-L51


So this could cause issues (specifically extra unknowns) when text is converted to tokens, then to ids, then back.