code: public void append(final CharBuffer cb) {
          if (cb == null) {
              return;
          }
          provideCapacity(length + cb.length);
          System.arraycopy(cb.c, 0, c, length, cb.length);
          length += cb.length;
      }
docs: Appends the contents of <code>cb</code> to the end of this CharBuffer.
  @param cb the CharBuffer to append or null