src/main/java/com/alipay/remoting/rpc/protocol/UserProcessorRegisterHelper.java
private static void registerUserProcessor(MultiInterestUserProcessor<?> processor,
                                              ConcurrentHashMap<String, UserProcessor<?>> userProcessors) {
        if (null == processor.multiInterest() || processor.multiInterest().isEmpty()) {
            throw new RuntimeException("Processor interest should not be blank!");
        }
        for (String interest : processor.multiInterest()) {
            UserProcessor<?> preProcessor = userProcessors.putIfAbsent(interest, processor);
            if (preProcessor != null) {
                String errMsg = "Processor with interest key ["
                                + interest
                                + "] has already been registered to rpc server, can not register again!";
                throw new RuntimeException(errMsg);
            }
        }

    }
private static void registerUserProcessor(MultiInterestUserProcessor<?> processor,
                                              ConcurrentHashMap<String, UserProcessor<?>> userProcessors) {
        if (null == processor.multiInterest() || processor.multiInterest().isEmpty()) {
            throw new RuntimeException("Processor interest should not be blank!");
        }
        for (String interest : processor.multiInterest()) {
            UserProcessor<?> preProcessor = userProcessors.putIfAbsent(interest, processor);
            if (preProcessor != null) {
                String errMsg = "Processor with interest key ["
                                + interest
                                + "] has already been registered to rpc server, can not register again!";
                throw new RuntimeException(errMsg);
            }
        }

    }
Help register multi-interest user processor.

@param processor  the processor with multi-interest need to be registered
@param userProcessors    the map of user processors