code: @Override
      public void writeBinary(Base64Variant b64variant, byte[] data, int offset, int len)
              throws IOException, JsonGenerationException
      {
          _verifyValueWrite("write binary value");
          // Starting quotes
          if (_outputTail >= _outputEnd) {
              _flushBuffer();
          }
          _outputBuffer[_outputTail++] = '\'';
          _writeBinary(b64variant, data, offset, offset+len);
          // and closing quotes
          if (_outputTail >= _outputEnd) {
              _flushBuffer();
          }
          _outputBuffer[_outputTail++] = '\'';
      }
docs: /*
  ********************************************************
  /* Output method implementations, base64-encoded binary
  ********************************************************