code: public boolean isPathAbsolute() {
      int start = hasWindowsDrive(mUri.getPath(), true) ? 3 : 0;
      return mUri.getPath().startsWith(SEPARATOR, start);
    }
docs: Tells whether or not the path component of the {@link AlluxioURI} is absolute.
  
  <p>
  A path is absolute if, and only if, it starts with root.
  </p>
  
  @return <tt>true</tt> if, and only if, the {@link AlluxioURI}'s path component is absolute