Can't get the text data when calling to_tf_dataset
I am working with the SST2 dataset, and am using TensorFlow 2.5
I'd like to convert it to a `tf.data.Dataset` by calling the `to_tf_dataset` method.
The following snippet is what I am using to achieve this:

```
from datasets import load_dataset
from transformers import DefaultDataCollator

data_collator = DefaultDataCollator(return_tensors="tf")
dataset = load_dataset("sst")

train_dataset = dataset["train"].to_tf_dataset(columns=['sentence'], label_cols="label", shuffle=True, batch_size=8,collate_fn=data_collator)
```
However, this only gets me the labels; the text--the most important part--is missing:

```
for s in train_dataset.take(1):
  print(s) #prints something like: ({}, <tf.Tensor: shape=(8,), ...>)
```

As you can see, it only returns the label part, not the data, as indicated by the empty dictionary, `{}`. So far, I've played with various settings of the method arguments, but to no avail; I do not want to perform any text processing at this time. On my quest to achieve what I want ( a `tf.data.Dataset`), I've consulted these resources:

[https://www.philschmid.de/huggingface-transformers-keras-tf](https://www.philschmid.de/huggingface-transformers-keras-tf)
[https://huggingface.co/docs/datasets/use_dataset.html?highlight=tensorflow](https://huggingface.co/docs/datasets/use_dataset.html?highlight=tensorflow)

I was surprised to not find more extensive examples on how to transform a Hugginface dataset to one compatible with TensorFlow.

If you could point me to where I am going wrong, please do so.
Thanks in advance for your support.

---
Edit: In the [docs](https://huggingface.co/docs/datasets/package_reference/main_classes.html#datasets.Dataset.to_tf_dataset), I found the following description:


_In general, only columns that the model can use as input should be included here (numeric data only)._

Does this imply that no textual, i.e., `string` data can be loaded?
