I noticed the treesitter imenu definitions for java in java-ts-mode.el have the following:
;; Imenu.
(setq-local treesit-simple-imenu-settings
'(("Class" \\`class_declaration\\' nil nil)
("Interface"
\\`interface_declaration\\' nil nil)
("Enum" \\`record_declaration\\' nil nil)
("Method"
\\`method_declaration\\' nil nil)))
(treesit-major-mode-setup))
The 3rd definition for enums should either be for “Record” if that was the intention or match against
\\`enum_declaration if it really was meant for enums.
Ben