groovy script in nifi 1.11 : unable to loasd FastStringService

[Chris Herssens]

Hello,

I try to implement a groovy script where I'm using jsonOutput.
With nifi 1.5 the script works, but If I'm try to use the same groovy
script with nifi 1.11.4, I get
"unable to load FastStringService"

example code :

class GroovyRecordSetWriter implements RecordSetWriter {
....
@Override
 WriteResult write(Record r) throws IOException {
...
def j = JsonOutput.toJson([name: 'John Doe', age: 42])
 out.write(j.getBytes())

...

Regards,
Chris