code: public BeanInvoker getWriteInvoker(String name) {
          BeanInvoker invoker;
          if (writeInvokers.containsKey(name)) {
              invoker = writeInvokers.get(name);
          } else {
              invoker = getInvoker(HandleType.SET, name);
              writeInvokers.put(name, invoker);
          }
          return invoker;
      }
docs: Returns the mutator for the property with the given name.
  
  @param name the name of the property
  @return the mutator method for the property, or null