--- old/jdk/src/java.base/share/classes/jdk/experimental/bytecode/ClassBuilder.java	2017-09-19 16:01:49.000000000 -0700
+++ new/jdk/src/java.base/share/classes/jdk/experimental/bytecode/ClassBuilder.java	2017-09-19 16:01:49.000000000 -0700
@@ -99,6 +99,9 @@
     }
 
     public C withMethod(CharSequence name, T type, Consumer<? super MethodBuilder<S, T, byte[]>> methodBuilder) {
+        if (name.toString().contains(".")) {
+            throw new IllegalArgumentException("Illegal method name " + name);
+        }
         MethodBuilder<S, T, byte[]> M = new MethodBuilder<>(thisClass, name, type, poolHelper, typeHelper);
         methodBuilder.accept(M);
         M.build(methods);