code: public Set<String> getPropAsSet(String key, String def) {
      return ImmutableSet.copyOf(LIST_SPLITTER.splitToList(getProp(key, def)));
    }
docs: Get the value of a comma separated property as a {@link Set} of strings.
  
  @param key property key
  @param def default value
  @return value (the default value if the property is not set) associated with the key as a {@link Set} of strings