Updated to run with jdk 11. I downloaded a sample epub file and
checked this. Note the addition of quotes around the $@. That is
needed to avoid this problem:

epubcheck test\ dir/accessible_epub_3.epub                                                                                                                                        
Unrecognized argument: "dir/accessible_epub_3.epub"

The quotes are needed to preserve 'test\ dir/accessible_epub_3.epub'
as a single argument (dir with space in it). Without the quotes
around "$@" it turns the one argument with a space into two and
the program fails.

okay?

Index: Makefile
===================================================================
RCS file: /cvs/ports/textproc/epubcheck/Makefile,v
diff -u -p -u -r1.10 Makefile
--- Makefile	15 Sep 2025 13:26:47 -0000	1.10
+++ Makefile	23 Dec 2025 19:41:51 -0000
@@ -4,6 +4,7 @@ COMMENT =	EPUB validator
 
 V =		5.3.0
 DISTNAME =	epubcheck-$V
+REVISION =	0
 
 CATEGORIES =	textproc
 
@@ -19,7 +20,7 @@ SITES =			https://github.com/w3c/epubche
 EXTRACT_SUFX =		.zip
 
 MODULES =		java
-MODJAVA_VER =		1.8+
+MODJAVA_VER =		11+
 RUN_DEPENDS =		java/javaPathHelper
 
 NO_BUILD =		Yes
Index: files/epubcheck
===================================================================
RCS file: /cvs/ports/textproc/epubcheck/files/epubcheck,v
diff -u -p -u -r1.1.1.1 epubcheck
--- files/epubcheck	23 Jun 2019 06:50:52 -0000	1.1.1.1
+++ files/epubcheck	23 Dec 2025 19:41:51 -0000
@@ -1,2 +1,3 @@
 #!/bin/sh
-`javaPathHelper -c epubcheck` -jar /usr/local/share/epubcheck/epubcheck.jar $@
+JAVACMD=$(javaPathHelper -c epubcheck)
+exec ${JAVACMD} -jar /usr/local/share/epubcheck/epubcheck.jar "$@"