code: @Override
      public String getDefaultMetaVariable() {
      	StringBuffer rv = new StringBuffer();
      	rv.append("[");
      	for (T t : enumType.getEnumConstants()) {
  			rv.append(t).append(" | ");
  		}
      	rv.delete(rv.length()-3, rv.length());
      	rv.append("]");
      	return rv.toString();
      }
docs: /*
  Returns all values of an enum type split by pipe.
  <tt>[ one | two | three]</tt>
  @see org.kohsuke.args4j.spi.OptionHandler#getDefaultMetaVariable()