[Python] AWS Step Functions - pass list into Glue's argument

Within my workflow I query DynamoDB for tables whose load_fail status equals 1.

If there is at least one table, Glue job needs to start with that list of tables as --source_tables argument.

Below is my entire state machine.

{
"Comment": "A description of my state machine",
"StartAt": "Query",
"States": {
"Query": {
"Type": "Task",
"Next": "Choice",
"Parameters": {
"TableName": "source_tables_load_status",
"KeyConditionExpression": "load_fail = :load_fail",
"ExpressionAttributeValues": {
":load_fail": {
"S": "1"
}
}
},
"Resource": "arn:aws:states:::aws-sdk:dynamodb:query",
"ResultSelector": {
"count.$": "$.Count",
"startTime.$": "$$.Execution.StartTime",
"items.$": "$.Items[*].table_name.S"
}
},
"Choice": {
"Type": "Choice",
"Choices": [
{
"Variable": "$.count",
"NumericGreaterThanEquals": 1,
"Next": "start_glue"
}
],
"Default": "Success"
},
"start_glue": {
"Type": "Task",
"Resource": "arn:aws:states:::glue:startJobRun",
"Parameters": {
"JobName": "data-moving-glue",
"Arguments": {
"--dynamodb_metadata_table": "metadata_table",
"--source_tables.$": "$.items"
}
},
"End": true
},
"Success": {
"Type": "Succeed"
}
}
}


Currently I'm getting an error caused by "--source_tables.$": "$.items".

Question is how to make "--source_tables":["dbo.Table_Two", "dbo.Table_Three"] working by state machine:

An error occurred while executing the state 'start_glue' (entered at the event id #9).
The Parameters '{"JobName":"data-moving-glue","Arguments":{"--dynamodb_metadata_table":"metadata_table","--source_tables":["dbo.Table_Two", "dbo.Table_Three"]}}'
could not be used to start the Task: [The value for the field '--source_tables' must be a STRING]

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