NativeImageResourceFileSystem should throw NPE when uri is null.

Author: jovanstevanovic

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/resources/NativeImageResourceFileSystemProvider.java

@@ -49,6 +49,7 @@
 import java.nio.file.attribute.FileAttributeView;
 import java.nio.file.spi.FileSystemProvider;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReadWriteLock;
@@ -140,6 +141,7 @@ public FileSystem newFileSystem(Path path, Map<String, ?> env) {
     public FileSystem getFileSystem(URI uri) {
         try {
             readLock.lock();
+            Objects.requireNonNull(uri);
             if (fileSystem == null) {
                 throw new FileSystemNotFoundException("The Native Image Resource File System is not present. " +
                                 "Please create a new file system using the `newFileSystem` operation before attempting any file system operations on resource URIs.");