Add @SuppressWarnings with comments.

Author: Gary Gregory

src/main/java/org/apache/commons/io/output/AbstractByteArrayOutputStream.java

@@ -303,6 +303,7 @@ protected void writeToImpl(final OutputStream out) throws IOException {
      * @see #reset()
      * @since 2.7
      */
+    @SuppressWarnings("resource") // The result InputStream MUIST be managed by the call site.
     protected <T extends InputStream> InputStream toInputStream(
             final InputStreamConstructor<T> isConstructor) {
         int remaining = count;

src/main/java/org/apache/commons/io/output/DemuxOutputStream.java

@@ -47,6 +47,7 @@ public OutputStream bindStream(final OutputStream output) {
      * @throws IOException
      *             if an error occurs
      */
+    @SuppressWarnings("resource") // we actually close the stream here
     @Override
     public void close() throws IOException {
         IOUtils.close(outputStreamThreadLocal.get());

src/main/java/org/apache/commons/io/output/ThresholdingOutputStream.java

@@ -69,6 +69,7 @@ public ThresholdingOutputStream(final int threshold) {
      *
      * @throws IOException if an error occurs.
      */
+    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.
     @Override
     public void write(final int b) throws IOException {
         checkThreshold(1);
@@ -83,6 +84,7 @@ public void write(final int b) throws IOException {
      *
      * @throws IOException if an error occurs.
      */
+    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.
     @Override
     public void write(final byte[] b) throws IOException {
         checkThreshold(b.length);
@@ -99,6 +101,7 @@ public void write(final byte[] b) throws IOException {
      *
      * @throws IOException if an error occurs.
      */
+    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.
     @Override
     public void write(final byte[] b, final int off, final int len) throws IOException {
         checkThreshold(len);
@@ -111,6 +114,7 @@ public void write(final byte[] b, final int off, final int len) throws IOExcepti
      *
      * @throws IOException if an error occurs.
      */
+    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.
     @Override
     public void flush() throws IOException {
         getStream().flush();