Too many commas are appended to a log message when propeties=false

[dekobon]

Here is an example of a message the ends up being invalid JSON:

{"v":0,"level":20,"name":"foo","hostname":"redacted","pid":378729,"time":"2021-11-29T01:48:36.216Z","msg":"Loaded into cache","src":{"file":"Cache.java","line":72,"func":"Cache$1.load"},"traceId":"d860e792e90939c655704880b989c2b8",,"thread":"http-nio-8080-exec-1[id=66,priority=5]"}