Sponge/Forge DummyThing

Plugins Plugin Development
1

Hello,

I have an issue where compiling my project with gradle I get the issue (I am trying to use SpongeForge for 1.12, as well Forge):
Execution failed for task ‘:reobfJar’.

java.util.zip.ZipException: duplicate entry: dummyThing

build.gradle
buildscript { repositories { maven { name = 'forge' url = 'http://files.minecraftforge.net/maven' } } 
dependencies {
    classpath 'net.minecraftforge.gradle:ForgeGradle:2.3-SNAPSHOT'
}

}

plugins {
id ‘org.spongepowered.plugin’ version ‘0.8.1’
}

apply plugin: ‘net.minecraftforge.gradle.forge’

version = pluginVersion

sourceCompatibility = ‘1.8’
targetCompatibility = ‘1.8’

allprojects {

configurations {
    spec
    compile.extendsFrom spec
}

minecraft {
    forgeVersion = '2555'
    mappings = 'snapshot_20171229'
}

repositories {
    mavenCentral()

    maven {
        url "http://repo.drnaylor.co.uk/artifactory/list/minecraft"
    }

    maven {
        name "luck-repo"
        url "https://repo.lucko.me/"
    }

    maven {
        url "https://jitpack.io"
    }
}

dependencies {
    compile 'com.warrenstrange:googleauth:1.1.2'

    spec 'org.spongepowered:spongeapi:7.0.0-BETA'
    spec 'org.spongepowered:spongeforge:1.12.2-2555-7.0.0-BETA-2800:dev'
    spec 'io.github.nucleuspowered:nucleus-api:1.2.0-SNAPSHOT-S7.0'
    spec fileTree(dir: 'libs', include: '*.jar')
    spec 'me.lucko.luckperms:luckperms-api:4.0'
}

jar {
    into('assets/fncore') {
        from 'assets/fncore'
    }

    from {
        (configurations.runtime - configurations.spec).collect {
            it.isDirectory() ? it : zipTree(it)
        }
    }
}

}

sponge.plugin.id = pluginId

>

Not sure where the issue is?