java.lang.string.substring.nocopy is not documented, but can be used to fix a difference in behavior with Hotspot as per eclipse-openj9/openj9#8102 (comment) ...
java.lang.StringIndexOutOfBoundsException: String index out of range: 16 at java.lang.String.substring(java/lang/String.java:1963) ~[?:1.8.0_212] at org.logstash ...