GraalVM is a polyglot virtual machine. In addition to that, it supports Ahead of Time, AOT, compilation of Java applications into native executable files via its native-image` compiler.
This directory contains directives to the compiler on what classes use reflection. These are currently stored in a file called tomcat-reflection.json in the META-INF/native-image/groupId/artifactId location.
This directory also contains resource directives, so that resource files normally included in a JAR file also get compiled into the executable image. These are currently stored in a file called tomcat-resource.json in the META-INF/native-image/groupId/artifactId location.