code: public void addInterface(Class<?> ifc) {
  
          LettuceAssert.notNull(ifc, "Interface type must not be null");
          LettuceAssert.isTrue(ifc.isInterface(), "Type must be an interface");
  
          this.interfaces.add(ifc);
      }
docs: Add a interface type that should be implemented by the resulting invocation proxy.
  
  @param ifc must not be {@literal null} and must be an interface type.