code: public void load(ByteArrayBuffer buffer)
      throws IOException
    {
      synchronized (this) {
        Source classPath = getClassPath();
      
        buffer.clear();
  
        int retry = 3;
        for (int i = 0; i < retry; i++) {
          long length = -1;
          
          try (InputStream is = classPath.inputStream()) {
            length = classPath.length();
            long lastModified = classPath.getLastModified();
  
            if (length < 0)
              throw new IOException("class loading failed because class file '" + classPath + "' does not have a positive length.  Possibly the file has been overwritten");
  
            buffer.setLength((int) length);
  
            int results = IoUtil.readAll(is, buffer.getBuffer(), 0, (int) length);
  
            if (results == length
                && length == classPath.length()
                && lastModified == classPath.getLastModified()) {
              return;
            }
  
            log.warning(L.l("{0}: class file length mismatch expected={1} received={2}.  The class file may have been modified concurrently.",
                  this, length, results));
          }
        }
      }
    }
docs: Loads the contents of the class file into the buffer.