code: public StructuredQueryDefinition wordConstraint(String constraintName, double weight, String... words) {
      return new WordConstraintQuery(constraintName, weight, words);
    }
docs: Matches the container specified by the constraint when it
  has at least one of the criteria words.
  @param constraintName    the constraint definition
  @param weight    the multiplier for the match in the document ranking
  @param words    the possible words to match
  @return    the StructuredQueryDefinition for the word constraint query