Providers loaded by java.nio.file.spi.FileSystemProvider (such as BouncyCastleProvider or SftpFileSystemProvider) cause native image compilation to fail with No instances of xxx are allowed in the image heap as this class should be initialized at image runtime.. However, adding --initialize-at-run-time=java.nio.file.spi.FileSystemProvider to setup results in Error: The class java.nio.file.spi.FileSystemProvider has already been initialized (from command line with 'java.nio.file.spi.FileSystemProvider'); it is too late to register java.nio.file.spi.FileSystemProvider for build-time initialization..

You can use this demo branch as a sample.
Run with ./mvnw clean package -Pnative -DskipTests.