docs: public static int[] getBodyToViewPosition(JTextArea view, String header, int start, int end) {
          validateView(view);
          validateHeader(header);
          validateStartEnd(start, end);
  
          if (!isValidStartEndForLength(start, end, view.getDocument().getLength())) {
              return INVALID_POSITION;
          }
  
          int excessChars = 0;
  
          int pos = 0;
          while ((pos = header.indexOf(HttpHeader.CRLF, pos)) != -1) {
              pos += 2;
              ++excessChars;
          }
  
          int len = view.getDocument().getLength();
          int bodyLen = len - header.length() + excessChars;
          if (bodyLen < 0 || start > bodyLen || end > bodyLen) {
              return INVALID_POSITION;
          }
  
          int finalStartPos = start + header.length() - excessChars;
          int finalEndPos = end + header.length() - excessChars;
          return new int[] { finalStartPos, finalEndPos };
      }