private void startCapture() {
    if (captureBuffer == null) {
      captureBuffer = new StringBuilder();
    }
    captureStart = index - 1;
  }
Reads the entire input from the given reader and parses it as JSON. The input must contain a
valid JSON value, optionally padded with whitespace.
<p>
Characters are read in chunks into an input buffer of the given size. Hence, wrapping a reader
in an additional <code>BufferedReader</code> likely won't improve reading performance.
</p>

@param reader
         the reader to read the input from
@param buffersize
         the size of the input buffer in chars
@throws IOException
          if an I/O error occurs in the reader
@throws ParseException
          if the input is not valid JSON
flatlaf-core/src/main/java/com/formdev/flatlaf/json/JsonParser.java