java.util.zip.ZipException: duplicate entry: META_INF/LICENSE.txt
<p>This is my first time using Java Web Start. This is for a demo version of my application. I have uploaded the JAR to my server, and created a JNLP file. When I run the file locally, I get the exception shown below.</p>

<p><a href="https://i.stack.imgur.com/Rt3jp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Rt3jp.png" alt="enter image description here"></a></p>

<p><a href="http://docs.oracle.com/javase/tutorial/deployment/deploymentInDepth/jnlpFileSyntax.html" rel="nofollow noreferrer">This</a> was the reference I was reading, and below is my JNLP file.</p>

<p>DerbyPro.jnlp</p>

<pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;jnlp spec="1.0+" codebase="" href=""&gt;
    &lt;information&gt;
        &lt;title&gt;Derby Pro&lt;/title&gt;
        &lt;vendor&gt;Neon Orb&lt;/vendor&gt;
        &lt;icon href="http://neonorb.com/images/derby-pro/derby-pro-icon-hd.png"/&gt;
        &lt;offline-allowed/&gt;
    &lt;/information&gt;

    &lt;resources&gt;
        &lt;j2se version="1.8+" href=
                "http://neonorb.com"/&gt;
        &lt;jar href="http://neonorb.com/clientportal/derby-pro-demo.jar"
             main="true" /&gt;
    &lt;/resources&gt;

    &lt;application-desc
            name="Derby Pro"
            main-class="com.neonorb.derbypro.main.DerbyPro"
            width="300"
            height="300"&gt;
    &lt;/application-desc&gt;

    &lt;update check="background"/&gt;
&lt;/jnlp&gt;
</code></pre>

<p>Here is my <code>build.gradle</code> file being called like this: <code>./gradlew -Pversion=0.0.0 -Pdemo=true fatJar</code></p>

<pre><code>group 'com.neonorb'

apply plugin: 'java'

sourceCompatibility = 1.8

project.description = 'Derby Pro is pinewood derby management software.'

//create a single Jar with all dependencies
task fatJar(type: Jar) {
    manifest {
        attributes 'Implementation-Version': version,
                'Main-Class': 'com.neonorb.derbypro.main.DerbyPro',
                'Demo': demo
    }
    baseName = project.name
    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
    with jar
}

repositories {
    mavenCentral()
    maven {
        url "http://www.sparetimelabs.com/maven2"
    }
    mavenLocal()
}

dependencies {
    compile files('dfalex-0.9.2.jar')
    compile 'com.neonorb:commons:+'
    compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.5.4'
    compile group: 'commons-cli', name: 'commons-cli', version: '1.3.1'
    compile group: 'org.apache.commons', name: 'commons-lang3', version: '3.4'
    compile group: 'org.controlsfx', name: 'controlsfx', version: '8.40.10'
    compile group: 'org.fxmisc.easybind', name: 'easybind', version: '1.0.3'
    compile group: 'org.scream3r', name: 'jssc', version: '2.8.0'
    compile group: 'com.sparetimelabs', name: 'purejavacomm', version: '0.0.28'
    compile 'net.java.dev.jna:jna:4.2.1'
    compile 'commons-io:commons-io:2.4'
    testCompile group: 'junit', name: 'junit', version: '4.11'
    testCompile 'net.jodah:concurrentunit:0.4.2'
}

//Native launchers

//Windows

buildscript {
    repositories {
        maven {
            url 'https://plugins.gradle.org/m2/'
        }
    }
    dependencies {
        classpath 'gradle.plugin.edu.sc.seis.gradle:launch4j:1.6.1'
    }
}

apply plugin: 'edu.sc.seis.launch4j'

launch4j {
    //outputDir = 'native/windows'
    bundledJrePath = 'jre'

    dontWrapJar = true
    jar = 'bin/derby-pro.jar'

    mainClassName = 'com.neonorb.derbypro.main.DerbyPro'
    icon = '../../src/main/resources/com/neonorb/derbypro/assets/derby-pro-icon-favicon.ico'
    outfile = 'DerbyPro.exe'

    companyName = 'Neon Orb'
    productName = 'Derby Pro'
}

//OS X

/*plugins {
    id "edu.sc.seis.macAppBundle" version "2.1.0"
}

macAppBundle {
    mainClassName = "com.example.myApp.Start"
    icon = "myIcon.icns"
    bundleJRE = true
    javaProperties.put("apple.laf.useScreenMenuBar", "true")
    backgroundImage = "doc/macbackground.png"
}*/
</code></pre>

<p>Here is the manifest directory.</p>

<p><a href="https://i.stack.imgur.com/YiKN0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YiKN0.png" alt="enter image description here"></a></p>

<p>And here is the manifest content.</p>

<pre><code>Manifest-Version: 1.0
Implementation-Version: 0.0.0
Main-Class: com.neonorb.derbypro.main.DerbyPro
Demo: true
</code></pre>