Nifi 1.13 Execute script raising issue "failed to process due to org.apache.nifi.processor.exception.ProcessException: javax.script.ScriptException: SyntaxError: no viable alternative at input 'import' "

import json
from org.apache.commons.io import IOUtils
from java.nio.charset import StandardCharsets
from org.apache.nifi.processor.io import StreamCallback,InputStreamCallback, OutputStreamCallback

class PyInputStreamCallback(InputStreamCallback):
 def __init__(self):
 self.json_content = {}
 def process(self, inputStream):
 text = IOUtils.toString(inputStream, StandardCharsets.UTF_8)
 print(" text %s " %text)

class OutputWrite(OutputStreamCallback):
 def __init__(self, obj):
 self.obj = obj
 def process(self, outputStream):
 outputStream.write(bytearray(json.dumps(self.obj).encode('utf')))
###end class###
flowfile = session.get()
if flowfile != None:
 py_is = PyInputStreamCallback()
 session.read(flowfile, py_is)
 flowfile = session.write(flowfile, OutputWrite(py_is.json_content))
 session.transfer(flowfile, REL_SUCCESS)
 session.commit()
 session.close()