EXTRA_QUESTIONNAIRE_JSON_STRING
A JSON encoded string extra for a questionnaire. This should only be used for questionnaires with size at most 512KB. For large questionnaires, use EXTRA_QUESTIONNAIRE_JSON_URI.
This is required unless EXTRA_QUESTIONNAIRE_JSON_URI is provided.
If this and EXTRA_QUESTIONNAIRE_JSON_URI are provided, EXTRA_QUESTIONNAIRE_JSON_URI takes precedence.