Expected field name not found when doing CSV file encrpytion

```sh
tokenize_pipeline --project="my-project" \
--region="asia-southeast1" \
--runner="DataflowRunner" \
--tempLocation="gs://my-bucket/temp" \
--workerMachineType="n1-standard-1" \
--sourceType="CSV_FILE" \
--csvHeaders="mobile_number,created_at" \
--inputPattern="gs://my-bucket/data/*" \
--outputBigQueryTable="my-project:my_dataset.my_table" \
--tokenizeColumns="$.mobile_number" \
--valueTokenizerFactoryFullClassName="com.google.cloud.solutions.autotokenize.encryptors.AesEcbValueTokenizerFactory" \
--keyMaterial="projects/123456789012/secrets/my_encryption_key/versions/1" \
--keyMaterialType=GCP_SECRET_KEY \
--usePublicIps=false \
--subnetwork="https://www.googleapis.com/compute/v1/projects/my-network/regions/asia-southeast1/subnetworks/my-subnet-prod"
```

```sh
com.google.cloud.solutions.autotokenize.common.JsonConvertor$JsonConversionException: org.apache.avro.AvroTypeException: Expected field name not found: encrypted_msisdn org.apache.beam.runners.dataflow.worker.GroupAlsoByWindowsParDoFn$1.output(GroupAlsoByWindowsParDoFn.java:187)
```