[IO-630] Deprecate

`org.apache.commons.io.output.NullOutputStream.NullOutputStream()` in
favor of `org.apache.commons.io.output.NullOutputStream.NULL_OUTPUT_STREAM`.

Author: Gary Gregory

src/changes/changes.xml

@@ -140,6 +140,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action issue="IO-628" dev="ggregory" type="update" due-to="Allon Mureinik">
         Migration to JUnit Jupiter #97.
       </action>
+      <action issue="IO-630" dev="ggregory" type="update" due-to="Gary Gregory">
+        Deprecate `org.apache.commons.io.output.NullOutputStream.NullOutputStream()` in favor of `org.apache.commons.io.output.NullOutputStream.NULL_OUTPUT_STREAM`.
+      </action>
     </release>
 
     <release version="2.6" date="2017-10-15" description="Java 7 required, Java 9 supported.">

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

@@ -298,7 +298,7 @@ public static Checksum checksum(final File file, final Checksum checksum) throws
             throw new IllegalArgumentException("Checksums can't be computed on directories");
         }
         try (InputStream in = new CheckedInputStream(new FileInputStream(file), checksum)) {
-            IOUtils.copy(in, new NullOutputStream());
+            IOUtils.copy(in, NullOutputStream.NULL_OUTPUT_STREAM);
         }
         return checksum;
     }

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

@@ -28,6 +28,18 @@
  */
 public class NullOutputStream extends OutputStream {
 
+    /**
+     * Deprecated in favor of {@link #NULL_OUTPUT_STREAM}. 
+     * 
+     * TODO: Will be private in 3.0.
+     * 
+     * @deprecated Use {@link #NULL_OUTPUT_STREAM}.
+     */
+    @Deprecated
+    public NullOutputStream() {
+        super();
+    }
+
     /**
      * A singleton.
      */

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

@@ -37,9 +37,8 @@ public class NullPrintStream extends PrintStream {
     /**
      * Constructs an instance.
      */
-    @SuppressWarnings("resource")
     public NullPrintStream() {
-        super(new NullOutputStream());
+        super(NullOutputStream.NULL_OUTPUT_STREAM);
     }
 
 }

src/test/java/org/apache/commons/io/IOUtilsCopyTestCase.java

@@ -83,7 +83,7 @@ public void testCopy_inputStreamToOutputStream() throws Exception {
     public void testCopy_inputStreamToOutputStream_IO84() throws Exception {
         final long size = (long)Integer.MAX_VALUE + (long)1;
         final InputStream  in  = new NullInputStream(size);
-        final OutputStream out = new NullOutputStream();
+        final OutputStream out = NullOutputStream.NULL_OUTPUT_STREAM;
 
         // Test copy() method
         assertEquals(-1, IOUtils.copy(in, out));

src/test/java/org/apache/commons/io/input/CountingInputStreamTest.java

@@ -76,7 +76,7 @@ public void testLargeFiles_IO84() throws Exception {
         final long size = (long)Integer.MAX_VALUE + (long)1;
         final NullInputStream mock    = new NullInputStream(size);
         final CountingInputStream cis = new CountingInputStream(mock);
-        final OutputStream out        = new NullOutputStream();
+        final OutputStream out        = NullOutputStream.NULL_OUTPUT_STREAM;
 
         // Test integer methods
         IOUtils.copyLarge(cis, out);

src/test/java/org/apache/commons/io/output/CountingOutputStreamTest.java

@@ -81,7 +81,7 @@ public void testLargeFiles_IO84() throws Exception {
         final long size = (long)Integer.MAX_VALUE + (long)1;
 
         final NullInputStream mock     = new NullInputStream(size);
-        final OutputStream nos         = new NullOutputStream();
+        final OutputStream nos         = NullOutputStream.NULL_OUTPUT_STREAM;
         final CountingOutputStream cos = new CountingOutputStream(nos);
 
         // Test integer methods

src/test/java/org/apache/commons/io/output/NullOutputStreamTest.java

@@ -40,7 +40,7 @@ private void process(final NullOutputStream nos) throws IOException {
 
     @Test
     public void testNewInstance() throws IOException {
-        try (final NullOutputStream nos = new NullOutputStream()) {
+        try (final NullOutputStream nos = NullOutputStream.NULL_OUTPUT_STREAM) {
             process(nos);
         }
     }