ClassCast Exception - ExecutionContextDataSource cannot be cast to java.lang.String

[abaratham-nlok]

Hello,

I am getting a ClassCastException when running a RabbitMQTriggered Java function

Core Tools Version: 4.0.4785 Commit hash: N/A (64-bit)
Function Runtime Version: 4.10.4.19213

Gradle dependency versions and azurefunctions plugin config:

plugins {
    id 'java'
    id "com.microsoft.azure.azurefunctions" version "1.11.0"
}

apply plugin: 'java'
apply plugin: "com.microsoft.azure.azurefunctions"

group 'com.anand.dsr'
version '0.0.1-SNAPSHOT'

sourceCompatibility = '1.8'
targetCompatibility = '1.8'

repositories {
    mavenCentral()
}

dependencies {
    implementation group: 'com.google.code.gson', name: 'gson', version: '2.9.1'
    implementation 'com.microsoft.azure.functions:azure-functions-java-library:2.0.1'
    implementation group: 'com.microsoft.azure.functions', name: 'azure-functions-java-library-rabbitmq', version: '2.0.1'
    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
    testImplementation "org.mockito:mockito-inline:4.1.0"
    testImplementation "org.mockito:mockito-junit-jupiter:4.1.0"
}

test {
    useJUnitPlatform()
}

azurefunctions {
    subscription = ''
    resourceGroup = ''
    appName = ''
    pricingTier = 'Consumption'
    region = 'eastus'
    runtime {
        os = 'linux'
    }
    localDebug = "transport=dt_socket,server=y,suspend=n,address=5005"
}

I have also tried downgrading the core tools and java runtime worker to version ~3, and azure-functions-java-library to 1.4.2.

Function definition:

    @FunctionName("requestProcessor")
    public void run(@RabbitMQTrigger(connectionStringSetting = "rabbitMQConnectionString", queueName = "dsr.test")
                                String inputMessage,
                    final ExecutionContext context)
    {
        context.getLogger().info("Successfully handled message: " + inputMessage);
    }

The error:

[2022-09-27T13:04:49.852Z] Exception: ClassCastException: com.microsoft.azure.functions.worker.binding.ExecutionContextDataSource cannot be cast to java.lang.String
[2022-09-27T13:04:49.852Z] Stack: java.lang.ClassCastException: com.microsoft.azure.functions.worker.binding.ExecutionContextDataSource cannot be cast to java.lang.String
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.binding.DataOperations.apply(DataOperations.java:99)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.binding.DataSource.computeByType(DataSource.java:56)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.binding.BindingDataStore.getDataByType(BindingDataStore.java:70)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.broker.ParameterResolver.resolve(ParameterResolver.java:65)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.broker.ParameterResolver.resolve(ParameterResolver.java:42)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.broker.JavaMethodExecutorImpl.execute(JavaMethodExecutorImpl.java:51)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.broker.JavaFunctionBroker.invokeMethod(JavaFunctionBroker.java:61)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:33)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:10)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.handler.MessageHandler.handle(MessageHandler.java:45)
[2022-09-27T13:04:49.852Z]      at com.microsoft.azure.functions.worker.JavaWorkerClient$StreamingMessagePeer.lambda$onNext$0(JavaWorkerClient.java:92)
[2022-09-27T13:04:49.852Z]      at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[2022-09-27T13:04:49.852Z]      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[2022-09-27T13:04:49.852Z]      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[2022-09-27T13:04:49.852Z]      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[2022-09-27T13:04:49.852Z]      at java.lang.Thread.run(Thread.java:750)

This seems to be happening because at runtime, ParameterResolver in the java worker library cannot find the @RabbitMQTrigger annotation to get the parameter name to map the inputMessage to a function parameter. I created my own @CustomTrigger annotation (below) and it started to work fine.

package com.microsoft.azure.functions.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PARAMETER})
public @interface CustomTrigger {
    String name() default "inputMessage";
}