code: public static byte[] encodeBytesURL(byte[] source, int pos, int limit, boolean wrap) {
          return Encoder.encodeBytes(source, pos, limit, wrap, true);
      }
docs: Encodes a fixed and complete byte buffer into a Base64url byte array.
  
  <pre><code>
  // Encodes "ell"
  FlexBase64.encodeStringURL("hello".getBytes("US-ASCII"), 1, 4, false);
  </code></pre>
  
  @param source the byte array to encode from
  @param pos the position to start encoding at
  @param limit the position to halt encoding at (exclusive)
  @param wrap whether or not to wrap at 76 characters with CRLFs
  @return a new byte array containing the encoded ASCII values