code: public ByteVector putByteArray(final byte[] b, final int off, final int len) {
          if (length + len > data.length) {
              enlarge(len);
          }
          if (b != null) {
              System.arraycopy(b, off, data, length, len);
          }
          length += len;
          return this;
      }
docs: Puts an array of bytes into this byte vector. The byte vector is
  automatically enlarged if necessary.
  
  @param b
  an array of bytes. May be <tt>null</tt> to put <tt>len</tt>
  null bytes into this byte vector.
  @param off
  index of the fist byte of b that must be copied.
  @param len
  number of bytes of b that must be copied.
  @return this byte vector.