Draft: StreamEncoder uses CharSequence::getChars

Author: mkarg

src/java.base/share/classes/sun/nio/cs/StreamEncoder.java

@@ -124,11 +124,15 @@ public void write(char[] cbuf, int off, int len) throws IOException {
     }
 
     public void write(String str, int off, int len) throws IOException {
+        implWrite(str, off, len);
+    }
+
+    private void implWrite(CharSequence csq, int off, int len) throws IOException {
         /* Check the len before creating a char buffer */
         if (len < 0)
             throw new IndexOutOfBoundsException();
         char[] cbuf = new char[len];
-        str.getChars(off, off + len, cbuf, 0);
+        csq.getChars(off, off + len, cbuf, 0);
         write(cbuf, 0, len);
     }
 
@@ -144,6 +148,11 @@ public void write(CharBuffer cb) throws IOException {
         }
     }
 
+    public Writer append(CharSequence csq) throws IOException {
+        implWrite(csq, 0, csq.length());
+        return this;
+    }
+
     public void flush() throws IOException {
         synchronized (lock) {
             ensureOpen();