code: private String lookupAttributeName(String attribute) {
      // .toLowerCase() because the original methods were not camel cased.
      String result = attribute.toLowerCase();
      String tmp;
  
      if (this.tokenAttributesMap != null) {
        tmp = this.tokenAttributesMap.get(attribute);
        result = (tmp == null) ? result : tmp;
      }
  
      return result;
    }
docs: Used to lookup the name of an attribute based on whether or not
  there is an alternate mapping supplied by
  {@link TokenAttributes#tokenAttributesMap}.
  
  @param attribute The name of the {@linkplain TokenAttributes} property to lookup.
  @return The mapped name, or the passed in name.