svoid forwardSwappableFunctionToObject(O o, S swappableMethodName, O target) {
  forwardSwappableFunctionToObject(o, swappableMethodName, target, swappableMethodName);
}

svoid forwardSwappableFunctionToObject(O o, S swappableMethodName, O target, S methodNameOnTarget) {
  if (o == null || target == null) ret;
  Class type = fieldType(o, swappableMethodName);
  if (type == null) ret; // field doesn't exist
  S proxyMethodName = type == Runnable.class ? "run" : "get";
  set(o, swappableMethodName, singleObjectMethodProxy2(type, target, proxyMethodName, methodNameOnTarget));
}

Began life as a copy of #1027671