public static Set<TokenType> getKeywordsValidBefore(final TokenType tokenType) {
        return getKeywordSet(tokenType, KEYWORDS_VALID_BEFORE);
    }
@return A set of {@link TokenType}s that are valid to appear in the query before tokenType.
stroom-query/stroom-query-api/src/main/java/stroom/query/api/token/TokenType.java