FTL stack trace ("~" means nesting-related):
- Failed at: #include "api-common-catalog.html.ftl" [in template "api-index.html.ftl" at line 39, column 9]

Java stack trace (for programmers):

freemarker.core._MiscTemplateException: [... Exception message was already printed; see it above ...]
at freemarker.core.Include.accept(Include.java:165)
at freemarker.core.Environment.visit(Environment.java:257)
at freemarker.core.MixedContent.accept(MixedContent.java:57)
at freemarker.core.Environment.visit(Environment.java:257)
at freemarker.core.Environment.process(Environment.java:235)
at freemarker.template.Template.process(Template.java:262)
at io.github.yedaxia.apidocs.doc.HtmlDocGenerator.generateIndex(HtmlDocGenerator.java:46)
at io.github.yedaxia.apidocs.doc.AbsDocGenerator.generateDocs(AbsDocGenerator.java:36)
at io.github.yedaxia.apidocs.Docs.buildHtmlDocs(Docs.java:30)
at com.ruiyin.T.main(T.java:19)
Caused by: freemarker.core.ParseException: Syntax error in template "api-common-catalog.html.ftl" in line 8, column 41:
Unknown built-in: "index". Help (latest version): http://freemarker.org/docs/ref_builtins.html; you're using FreeMarker 2.3.21.
The alphabetical list of built-ins:
abs, ancestors,
boolean, byte,
c, cap_first, capitalize, ceiling, children, chop_linebreak, chunk, contains,
date, date_if_unknown, datetime, datetime_if_unknown, default, double,
ends_with, ensure_ends_with, ensure_starts_with, eval, exists,
first, float, floor,
groups,
has_content, html,
if_exists, index_of, int, interpret, is_boolean, is_collection, is_date, is_date_like, is_date_only, is_datetime, is_directive, is_enumerable, is_hash, is_hash_ex, is_indexable, is_infinite, is_macro, is_method, is_nan, is_node, is_number, is_sequence, is_string, is_time, is_transform, is_unknown_date_like, iso, iso_h, iso_h_nz, iso_local, iso_local_h, iso_local_h_nz, iso_local_m, iso_local_m_nz, iso_local_ms, iso_local_ms_nz, iso_local_nz, iso_m, iso_m_nz, iso_ms, iso_ms_nz, iso_nz, iso_utc, iso_utc_fz, iso_utc_h, iso_utc_h_nz, iso_utc_m, iso_utc_m_nz, iso_utc_ms, iso_utc_ms_nz, iso_utc_nz,
j_string, join, js_string, json_string,
keep_after, keep_before, keys,
last, last_index_of, left_pad, length, long, lower_case,
matches,
namespace, new, node_name, node_namespace, node_type, number, number_to_date, number_to_datetime, number_to_time,
parent,
remove_beginning, remove_ending, replace, reverse, right_pad, root, round, rtf,
seq_contains, seq_index_of, seq_last_index_of, short, size, sort, sort_by, split, starts_with, string, substring,
time, time_if_unknown, trim,
uncap_first, upper_case, url, url_path,
values,
web_safe, word_list,