An illegal reflective access operation has occurred

[uncovery]

Environment info

• BlockMap version: BlockMap-cli-1.5.1.jar
• Java version: openjdk version "12.0.2" 2019-07-16
  OpenJDK Runtime Environment 19.3 (build 12.0.2+9)
  OpenJDK 64-Bit Server VM 19.3 (build 12.0.2+9, mixed mode, sharing)
• Operating system: CentOS 7, Linux 3.10.0-862.2.3.el7.x86_64

Description

I get the following warnings:

WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.gson.internal.reflect.UnsafeReflectionAccessor (file:/home/minecraft/server/blockmap/BlockMap-cli-1.5.1.jar) to constructor java.util.Optional()
WARNING: Please consider reporting this to the maintainers of com.google.gson.internal.reflect.UnsafeReflectionAccessor
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

Steps to reproduce

1. java -jar BlockMap.jar -v render ./region --create-big-image --min-X=-2048 --max-X=2048 --min-Z=-2048 --max-Z=2048 -o ./png --create-tile-html

[piegamesde]

Please consider reporting this to the maintainers of com.google.gson.internal.reflect.UnsafeReflectionAccessor

BlockMap only uses GSON as dependency, I do not maintain that class. You should file the bug to them instead.

This may be a duplicate of google/gson#1540