docs: public JsonValue parse(Reader reader, int buffersize) throws IOException {
          if (reader == null) {
              throw new NullPointerException("reader is null");
          }
          if (buffersize <= 0) {
              throw new IllegalArgumentException("buffersize is zero or negative");
          }
          this.reader = reader;
          buffer = new char[buffersize];
          bufferOffset = 0;
          index = 0;
          fill = 0;
          line = 1;
          lineOffset = 0;
          current = 0;
          captureStart = -1;
          read();
          return readValue();
      }