No value has been specified for property mainClassName

[nogo]

Please check the (User Guide)[http://imperceptiblethoughts.com/shadow] before submitting "how do I do 'x'?" questions!

Shadow Version

2.0.1

Gradle Version

4.3

Expected Behavior

work as in 4.2.1

Actual Behavior

:shadowJar
A problem was found with the configuration of task ':shadowJar'. Registering invalid inputs and outputs via TaskInputs and TaskOutputs methods has been deprecated and is scheduled to be removed in Gradle 5.0.

• No value has been specified for property 'mainClassName'.

Build script

Extract of my build script

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'com.github.johnrengelman.shadow'

mainClassName = 'com.package.to.Class'

shadowJar {
baseName = 'launcher'
classifier = null
version = null
}

[andrii-kovalenko-ct]

same here, just have updated to gradle 4.3, shadow version 2.0.1 (as before)

[schnapster]

Fwiw the resulting jar still works (for me) despite the warning, what actually breaks with gradle 4.3 is runShadow.

[lbergelson]

I'm also seeing this with shadow 2.0.2 and gradle 4.4.

[sgnewson]

Might just be a missing mainClassName = 'com.package.to.Class' in this plugin's build?

[jonwagner]

If you define mainClassName before you apply the plugin, the build succeeds. Sounds like an issue with initialization order.

[sgnewson]

Can confirm, placing the mainClassName after the application plugin and before the shadow plugin lines removes the warnings

[Mat2095]

I'm also seeing this with shadow 2.0.2 and gradle 4.5.

[johnrengelman]

yeah, i need to improve this, but the workaround is to specify mainClassName before applying the Shadow plugin.

[RaviH]

With the build.gradle below, I still get:

A problem was found with the configuration of task ':vertx-web:shadowJar'. Registering invalid inputs and outputs via TaskInputs and TaskOutputs methods has been deprecated and is scheduled to be removed in Gradle 5.0.
- No value has been specified for property 'mainClassName'.
The SimpleWorkResult type has been deprecated and is scheduled to be removed in Gradle 5.0. Please use WorkResults.didWork() instead.

> Task :vertx-web:startShadowScripts 
Using TaskInputs.file() with something that doesn't resolve to a File object has been deprecated and is scheduled to be removed in Gradle 5.0. Use TaskInputs.files() instead.

Gradle version: 4.4

plugins {
    id 'application'
    id 'com.github.johnrengelman.shadow' version '2.0.1'
}

mainClassName = 'io.vertx.core.Launcher'
def vertxVersion = '3.5.0'
def mainVerticleName = 'com.charter.devtool.web.vertx.verticle.MainVerticle'
def watchForChange = 'src/**/*'
def doOnChange = './gradlew classes'

dependencies {
    compile project(':devtool-core')
    compile project(':devtool-db')
    compile project(':devtool-stash-client')

    compile('io.vertx:vertx-core:3.5.0')
    compile('io.vertx:vertx-web:3.5.0')
    compile('com.zandero:rest.vertx:0.7.5')
    compile('org.eclipse.jgit:org.eclipse.jgit:4.9.2.201712150930-r')
    compile('com.github.salomonbrys.kodein:kodein:4.1.0')
}

shadowJar {
    mainClassName = 'io.vertx.core.Launcher'
    classifier = 'fat'
    manifest {
        attributes "Main-Verticle": mainVerticleName
    }
    mergeServiceFiles {
        include 'META-INF/services/io.vertx.core.spi.VerticleFactory'
    }
}

run {
    args = ['run', mainVerticleName, "--redeploy=$watchForChange", "--launcher-class=$mainClassName", "--on-redeploy=$doOnChange"]
}

[Mat2095]

Try something like

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:2.0.2'
    }
}

plugins {
    id "application"
}

mainClassName = '...'

apply plugin: 'com.github.johnrengelman.shadow'

[...]

[ljohnston]

The above workaround fixes the 'mainClassName' issue, but does not address the following warning:

Task :vertx-web:startShadowScripts
Using TaskInputs.file() with something that doesn't resolve to a File object has been deprecated and is scheduled to be removed in Gradle 5.0. Use TaskInputs.files() instead.

[ljohnston]

After a little more digging, seems like this has been fixed but not yet released. Thx @johnrengelman ! Looking forward to 2.0.3.