code: public MethodHandleConstant addMethodHandle(MethodHandleType mhType,
                                                ConstantPoolEntry cpEntry)
    {
      MethodHandleConstant entry = getMethodHandle(mhType, cpEntry);
  
      if (entry != null) {
        return entry;
      }
  
      entry = new MethodHandleConstant(this, _entries.size(), mhType, cpEntry);
  
      addConstant(entry);
  
      return entry;
    }
docs: Adds a method ref constant.