bug#81551: 31.0.91; Electric-pair-mode should support Java's text blocks in java-mode, java-ts-mode

Java >= 15 has support for "text blocks", multi-line strings delimited
by triple quotation marks similar to Python, e.g.:

"""
This is how Java's
multi-line strings look like.
"""

In my configuration, I added support for this to electric-pair-mode like so:

(add-hook 'java-mode-hook
          (lambda ()
            (setq-local electric-pair-pairs
                        (cons '("\"\"\"" . "\"\"\"") electric-pair-pairs))))

and similar for java-ts-mode.  I could prepare a patch that adds this to
java-ts-mode.el if this is the proper way to implement this.

But is there a better way for mode-specific customization of
electric-pair-mode?  The docstring of electric-pair-pairs says that it's
a fallback variable and that it can be overridden via a mode's syntax
table, but do syntax tables support this type of multi-character
delimiter?

FWIW, python.el and other modes included in Emacs seem to implement
multi-character electric pairs via adding a mode-specific function to
`post-self-insert-hook' instead of this built-in functionality.

Rudi