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

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

    }
public static void registerUserProcessor ( UserProcessor < ? > processor , ConcurrentHashMap < String , UserProcessor < ? > > userProcessors ) { if ( null == processor ) { throw new RuntimeException ( "User processor should not be null!" ) ; } if ( processor instanceof MultiInterestUserProcessor ) { registerUserProcessor ( ( MultiInterestUserProcessor ) processor , userProcessors ) ; } else { if ( StringUtils . isBlank ( processor . interest ( ) ) ) { throw new RuntimeException ( "Processor interest should not be blank!" ) ; } UserProcessor < ? > preProcessor = userProcessors . putIfAbsent ( processor . interest ( ) , processor ) ; if ( preProcessor != null ) { String errMsg = "Processor with interest key [" + processor . interest ( ) + "] has already been registered to rpc server, can not register again!" ; throw new RuntimeException ( errMsg ) ; } } }
Help register single-interest user processor.

@param processor  the processor need to be registered
@param userProcessors   the map of user processors
Help register single - interest user processor .