JSON workflow failing for PrintMessage Step

PrintMessage workflow fails with this error :
java.lang.RuntimeException: javax.script.ScriptException: :1:6 Expected ; but found 2.2
doing 2.2

The input json workflow looks like this
{
"id": "test-workflow",
"version": 1,
"dataType": "com.example.poc.WorkflowData",
"steps": [
{
"id": "print",
"stepType": "com.example.poc.PrintMessage",
"inputs": {
"message": "'doing 2.2'"
}
}
]
}

Start by running the supplied JSON workflow and trace the PrintMessage step from its message input through the script evaluation that raises ScriptException. Compare the quoted message value with the evaluator's expected syntax; done means the workflow executes successfully and prints doing 2.2.

Written by the indexing model from the issue text.