code: public static boolean containsNone(String str, String invalidChars) {
        if (str == null || invalidChars == null) {
            return true;
        }
        return containsNone(str, invalidChars.toCharArray());
    }
docs: <p>Checks that the String does not contain certain characters.</p>
  
  <p>A <code>null</code> String will return <code>true</code>.
  A <code>null</code> invalid character array will return <code>true</code>.
  An empty String ("") always returns true.</p>
  
  <pre>
  GosuStringUtil.containsNone(null, *)       = true
  GosuStringUtil.containsNone(*, null)       = true
  GosuStringUtil.containsNone("", *)         = true
  GosuStringUtil.containsNone("ab", "")      = true
  GosuStringUtil.containsNone("abab", "xyz") = true
  GosuStringUtil.containsNone("ab1", "xyz")  = true
  GosuStringUtil.containsNone("abz", "xyz")  = false
  </pre>
  
  @param str  the String to check, may be null
  @param invalidChars  a String of invalid chars, may be null
  @return true if it contains none of the invalid chars, or is null
  @since 2.0