src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java

@@ -151,13 +151,11 @@
 
         // additional module(s) specified by --add-modules
         boolean addAllDefaultModules = false;
         boolean addAllSystemModules = false;
         boolean addAllApplicationModules = false;
-        String propValue = getAndRemoveProperty("jdk.module.addmods");
-        if (propValue != null) {
-            for (String mod: propValue.split(",")) {
+        for (String mod: getExtraAddModules()) {
                 switch (mod) {
                     case ALL_DEFAULT:
                         addAllDefaultModules = true;
                         break;
                     case ALL_SYSTEM:

@@ -168,14 +166,13 @@
                         break;
                     default :
                         roots.add(mod);
                 }
             }
-        }
 
         // --limit-modules
-        propValue = getAndRemoveProperty("jdk.module.limitmods");
+        String propValue = getAndRemoveProperty("jdk.module.limitmods");
         if (propValue != null) {
             Set<String> mods = new HashSet<>();
             for (String mod: propValue.split(",")) {
                 mods.add(mod);
             }

@@ -390,10 +387,36 @@
             }
             return ModuleFinder.of(paths);
         }
     }
 
+    /**
+     * Returns the set of module names specified via --add-modules options
+     * on the command line
+     */
+    private static Set<String> getExtraAddModules() {
+        String prefix = "jdk.module.addmods.";
+        int index = 0;
+
+        // the system property is removed after decoding
+        String value = getAndRemoveProperty(prefix + index);
+        if (value == null) {
+            return Collections.emptySet();
+        }
+
+        Set<String> modules = new HashSet<>();
+        while (value != null) {
+            for (String s : value.split(",")) {
+                if (s.length() > 0) modules.add(s);
+            }
+
+            index++;
+            value = getAndRemoveProperty(prefix + index);
+        }
+
+        return modules;
+    }
 
     /**
      * Process the --add-reads options to add any additional read edges that
      * are specified on the command-line.
      */