code: public static boolean isValidJson (@Nonnull @WillClose final Reader aReader)
    {
      ValueEnforcer.notNull (aReader, "Reader");
  
      return _validateJson (StreamHelper.getBuffered (aReader)).isValid ();
    }
docs: Check if the passed reader can be resembled to valid Json content. This is
  accomplished by fully parsing the Json each time the method is called. This
  consumes <b>less memory</b> than calling any of the <code>read...</code>
  methods and checking for a non-<code>null</code> result.
  
  @param aReader
  The reader to use. May not be <code>null</code>.
  @return <code>true</code> if the Json is valid according to the version,
  <code>false</code> if not