[IO-811] StreamIterator fails to close its internal Stream

Test PR coming next

Author: garydgregory

src/changes/changes.xml

@@ -63,6 +63,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix" issue="IO-811" due-to="Adam Rauch, Gary Gregory">
         FileUtils.iterateFiles(File, String[], boolean) fails to close its internal Stream.
       </action>
+      <action dev="ggregory" type="fix" issue="IO-811" due-to="Adam Rauch, Gary Gregory">
+        StreamIterator fails to close its internal Stream.
+      </action>
     </release>
     <release version="2.14.0" date="2023-09-24" description="Java 8 is required.">
       <!-- FIX -->

src/main/java/org/apache/commons/io/StreamIterator.java

@@ -45,15 +45,16 @@ final class StreamIterator<E> implements Iterator<E>, Closeable {
      * @param stream The stream iterate.
      * @return A new iterator.
      */
-    @SuppressWarnings("resource") // Caller MUST close or iterate to the end.
     public static <T> Iterator<T> iterator(final Stream<T> stream) {
-        return new StreamIterator<>(stream).iterator;
+        return new StreamIterator<>(stream);
     }
 
     private final Iterator<E> iterator;
 
     private final Stream<E> stream;
 
+    private boolean closed;
+
     private StreamIterator(final Stream<E> stream) {
         this.stream = Objects.requireNonNull(stream, "stream");
         this.iterator = stream.iterator();
@@ -64,11 +65,16 @@ private StreamIterator(final Stream<E> stream) {
      */
     @Override
     public void close() {
+        closed = true;
         stream.close();
     }
 
     @Override
     public boolean hasNext() {
+        if (closed) {
+            // Calling Iterator#hasNext() on a closed java.nio.file.FileTreeIterator causes an IllegalStateException.
+            return false;
+        }
         final boolean hasNext = iterator.hasNext();
         if (!hasNext) {
             close();