--- a/src/jdk.internal.opt/share/classes/jdk/internal/joptsimple/OptionalArgumentOptionSpec.java	Wed Jun 06 13:06:21 2018 +0100
+++ b/src/jdk.internal.opt/share/classes/jdk/internal/joptsimple/OptionalArgumentOptionSpec.java	Wed Jun 06 15:36:29 2018 +0200
@@ -31,7 +31,7 @@
  *
  * The MIT License
  *
- * Copyright (c) 2004-2014 Paul R. Holser, Jr.
+ * Copyright (c) 2004-2015 Paul R. Holser, Jr.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
@@ -55,7 +55,7 @@
 
 package jdk.internal.joptsimple;
 
-import java.util.Collection;
+import java.util.List;
 
 /**
  * Specification of an option that accepts an optional argument.
@@ -68,7 +68,7 @@
         super( option, false );
     }
 
-    OptionalArgumentOptionSpec( Collection<String> options, String description ) {
+    OptionalArgumentOptionSpec( List<String> options, String description ) {
         super( options, false, description );
     }
 
@@ -77,7 +77,7 @@
         if ( arguments.hasMore() ) {
             String nextArgument = arguments.peek();
 
-            if ( !parser.looksLikeAnOption( nextArgument ) )
+            if ( !parser.looksLikeAnOption( nextArgument ) && canConvertArgument( nextArgument ) )
                 handleOptionArgument( parser, detectedOptions, arguments );
             else if ( isArgumentOfNumberType() && canConvertArgument( nextArgument ) )
                 addArguments( detectedOptions, arguments.next() );