code: public CommandLine setCaseInsensitiveEnumValuesAllowed(boolean newValue) {
          getCommandSpec().parser().caseInsensitiveEnumValuesAllowed(newValue);
          for (CommandLine command : getCommandSpec().subcommands().values()) {
              command.setCaseInsensitiveEnumValuesAllowed(newValue);
          }
          return this;
      }
docs: Sets whether the parser should ignore case when converting arguments to {@code enum} values. The default is {@code false}.
  When set to true, for example, for an option of type <a href="https://docs.oracle.com/javase/8/docs/api/java/time/DayOfWeek.html">java.time.DayOfWeek</a>,
  values {@code MonDaY}, {@code monday} and {@code MONDAY} are all recognized if {@code true}.
  <p>The specified setting will be registered with this {@code CommandLine} and the full hierarchy of its
  subcommands and nested sub-subcommands <em>at the moment this method is called</em>. Subcommands added
  later will have the default setting. To ensure a setting is applied to all
  subcommands, call the setter last, after adding subcommands.</p>
  @param newValue the new setting
  @return this {@code CommandLine} object, to allow method chaining
  @since 3.4