in log4j-converter-config/src/main/java/org/apache/logging/converter/config/internal/v1/layout/TTCCLayoutParser.java [108:127]
public void setDateFormat(String dateFormat) {
switch (dateFormat.toUpperCase(Locale.ROOT)) {
case ABSOLUTE:
this.dateFormat = ABSOLUTE_FORMAT;
break;
case DATE:
this.dateFormat = DATE_FORMAT;
break;
case ISO8601:
this.dateFormat = ISO8601_FORMAT;
break;
case RELATIVE:
this.dateFormat = RELATIVE;
break;
case NULL:
this.dateFormat = null;
break;
default:
}
}