code: public static boolean isValidJson (@Nonnull final IHasInputStream aISP, @Nonnull final Charset aFallbackCharset)
    {
      ValueEnforcer.notNull (aISP, "InputStreamProvider");
      ValueEnforcer.notNull (aFallbackCharset, "FallbackCharset");
  
      final InputStream aIS = aISP.getInputStream ();
      if (aIS == null)
      {
        if (LOGGER.isWarnEnabled ())
          LOGGER.warn ("Failed to open Json InputStream from " + aISP);
        return false;
      }
      return isValidJson (aIS, aFallbackCharset);
    }
docs: Check if the passed input stream can be resembled to valid Json content.
  This is accomplished by fully parsing the Json file 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 aISP
  The resource to be parsed. May not be <code>null</code>.
  @param aFallbackCharset
  The charset to be used for reading the Json file in case no BOM is
  present. May not be <code>null</code>.
  @return <code>true</code> if the file can be parsed without error,
  <code>false</code> if not