Index: gradle.properties
===================================================================
diff -u -N -rd3bece41b0827e852489f558152bb3f49e218193 -r650bca3ef095d09a5354240e7d2bafb6fc524122
--- gradle.properties	(.../gradle.properties)	(revision d3bece41b0827e852489f558152bb3f49e218193)
+++ gradle.properties	(.../gradle.properties)	(revision 650bca3ef095d09a5354240e7d2bafb6fc524122)
@@ -151,6 +151,19 @@
 eclipse_bin_dir = bin
 eclipse_debug = false
 
+## IMPORTANT for headless build
+# to enable `gradle jalviewjs` headless build you MUST set
+# j2s.config.altfileproperty = org.jalview.jalviewjsj2sfilename
+# (or set to whatever value jalviewjs_j2s_alt_file_property is set to)
+# in your ./.j2s file
+# OR run the task `gradle jalviewjsEnableAltFileProperty` to do that for you (before headless build task)
+jalviewjs_j2s_alt_file_property = org.jalview.jalviewjsj2sfilename
+jalviewjs_j2s_alt_settings = build/jalviewjs/config/j2s
+
+# these are used for actual .j2s file to pass on to alt j2s file
+jalviewjs_j2s_settings = .j2s
+jalviewjs_j2s_alt_file_property_config = j2s.config.altfileproperty
+
 # for developing in Eclipse as IDE, set this to automatically copy current swingjs/net.sf.j2s.core.jar to your dropins dir
 jalviewjs_eclipseIDE_auto_copy_j2s_plugin = false
 # Override this in a local.properties file
@@ -162,7 +175,7 @@
 jalviewjs_libjs_dir = utils/jalviewjs/libjs
 jalviewjs_site_resource_dir = utils/jalviewjs/site-resources
 jalviewjs_classlists_dir = utils/jalviewjs/classlists
-jalviewjs_j2s_settings = .j2s
+jalviewjs_classlist_jalview = utils/jalviewjs/_j2sclasslist.txt
 #jalviewjs_eclipse_workspace = ~/tmp/eclipse-workspace
 # these 3 files/dirs found in build/jalviewjs
 jalviewjs_eclipse_tmp_dropins_dir = eclipse_dropins