Given: existing class (bytecode)

Required: create a new class based on the existing class, replacing the static block initializer (not appending code)

So far, the following code appends commands to the static block

Class templateClass;
String newFQCN;
DynamicType.Unloaded unloaded = new ByteBuddy()
        .redefine(templateClass) 
        .name(newFQCN)
        .invokable(ElementMatchers.isTypeInitializer())
        .intercept(new Implementation.Simple(
                (mv, ctx, method) -> {
                    StackManipulation body =
                            generateClinit(method.getDeclaringType().asErasure()); 
                            // returns "StackManipulation", new code for the static block

                    StackManipulation.Size size = body.apply(mv, ctx);
                    mv.visitInsn(Opcodes.RETURN);
                    return new ByteCodeAppender.Size(
                            size.getMaximalSize(),
                            method.getStackSize()
                    );
                }
        ))
        .make();

Please recommend code edits that ensure replacing the static block, not appending code to it.