oops, forgot to add this

runtime/src/main/java/org/capnproto/GeneratedClassSupport.java

@@ -0,0 +1,11 @@
+package org.capnproto;
+
+public final class GeneratedClassSupport {
+    public static byte[] decodeRawBytes(String s) {
+        try {
+            return s.getBytes("ISO_8859-1");
+        } catch (Exception e) {
+            throw new Error("could not decode raw bytes from String");
+        }
+    }
+}