This is a copy of `org.jetbrains.annotations.Nls` from IntelliJ. It's need in the build because Kotlin depends on annotations-13.0, an older version where Nls doesn't have `capitalization`, whereas new versions of the IntelliJ platform reference it in the bytecode. Since we intentionally remove the newer annotations artifact from the intellij-core dependency and use version 13.0 in the build, javac wouldn't find the class file Nls$Capitalization referenced in the bytecode, and would report a non-suppressible warning for each usage site of it in IntelliJ binaries.