code: public void setCaseLevel(boolean flag) {
          checkNotFrozen();
          if(flag == isCaseLevel()) { return; }
          CollationSettings ownedSettings = getOwnedSettings();
          ownedSettings.setFlag(CollationSettings.CASE_LEVEL, flag);
          setFastLatinOptions(ownedSettings);
      }
docs: <p>
  When case level is set to true, an additional weight is formed between the SECONDARY and TERTIARY weight, known
  as the case level. The case level is used to distinguish large and small Japanese Kana characters. Case level
  could also be used in other situations. For example to distinguish certain Pinyin characters. The default value
  is false, which means the case level is not generated. The contents of the case level are affected by the case
  first mode. A simple way to ignore accent differences in a string is to set the strength to PRIMARY and enable
  case level.
  <p>
  See the section on <a href="http://userguide.icu-project.org/collation/architecture">case
  level</a> for more information.
  
  @param flag
  true if case level sorting is required, false otherwise
  @see #setCaseLevelDefault
  @see #isCaseLevel