code: public static CcgSyntaxTree createTerminal(SyntacticCategory syntax,
        SyntacticCategory originalSyntax, int spanStart, int spanEnd, List<String> words,
        List<String> posTags, HeadedSyntacticCategory headedSyntax) {
      Preconditions.checkNotNull(words);
      Preconditions.checkNotNull(posTags);
      return new CcgSyntaxTree(syntax, originalSyntax, spanStart, spanEnd, null, null, words,
          posTags, headedSyntax);
    }
docs: Create a terminal CCG parse tree, with an optional unary rule application.
  The tree has {@code syntax} as its root syntactic category, and spans the
  given set of {@code words} and {@code posTags}. {@code spanStart} and
  {@code spanEnd} are the word indexes of the tree's span in the sentence.
  
  @param syntax
  @param originalSyntax
  @param spanStart
  @param spanEnd
  @param words
  @param posTags
  @param headedSyntax
  @return