Getting rid of cast in favor of pattern matching for instanceof

Author: mkarg

src/java.base/share/classes/java/io/OutputStreamWriter.java

@@ -226,8 +226,8 @@ public void write(String str, int off, int len) throws IOException {
 
     @Override
     public Writer append(CharSequence csq) throws IOException {
-        if (csq instanceof CharBuffer) {
-            se.write((CharBuffer) csq);
+        if (csq instanceof CharBuffer cb) {
+            se.write(cb);
         } else {
             super.append(csq);
         }