Can't build with gradle

What does this error msg mean?

FAILURE: Build failed with an exception.

* What went wrong:
Could not resolve all dependencies for configuration ':compile'.
> Could not find com.jme3:xmlpull-xpp3:3.0.0.20140325-SNAPSHOT.
  Searched in the following locations:
      https://jcenter.bintray.com/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/maven-metadata.xml
      https://jcenter.bintray.com/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.pom
      https://jcenter.bintray.com/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.jar
      https://repo1.maven.org/maven2/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/maven-metadata.xml
      https://repo1.maven.org/maven2/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.pom
      https://repo1.maven.org/maven2/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.jar
      https://mvnrepository.com/artifact/cz.advel.jbullet/jbullet/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/maven-metadata.xml
      https://mvnrepository.com/artifact/cz.advel.jbullet/jbullet/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.pom
      https://mvnrepository.com/artifact/cz.advel.jbullet/jbullet/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.jar
      https://mvnrepository.com/artifact/org.cogchar/ext.bundle.opengl.jmonkey/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/maven-metadata.xml
      https://mvnrepository.com/artifact/org.cogchar/ext.bundle.opengl.jmonkey/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.pom
      https://mvnrepository.com/artifact/org.cogchar/ext.bundle.opengl.jmonkey/com/jme3/xmlpull-xpp3/3.0.0.20140325-SNAPSHOT/xmlpull-xpp3-3.0.0.20140325-SNAPSHOT.jar
  Required by:
      :spaceworld:unspecified > org.cogchar:ext.bundle.opengl.jmonkey:1.1.3

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

My build.gradle

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'eclipse'
apply plugin: 'idea'

mainClassName = 'spaceworld.SpaceUFO'

repositories {
    jcenter()
}

ext.jmeVersion = "[3.1,)"

project(":assets") {
    apply plugin: "java"

    buildDir = rootProject.file("build/assets")

    sourceSets {
        main {
            resources {
                srcDir '.'
            }
        }
    }
}
repositories {
    mavenCentral()
    maven {
        url "https://mvnrepository.com/artifact/cz.advel.jbullet/jbullet"

    }
    maven {

        url "https://mvnrepository.com/artifact/org.cogchar/ext.bundle.opengl.jmonkey"

    }
}



dependencies {

    compile "org.jmonkeyengine:jme3-core:$jmeVersion"
    compile "org.jmonkeyengine:jme3-desktop:$jmeVersion"
    compile "org.jmonkeyengine:jme3-lwjgl:$jmeVersion"
    compile "org.jmonkeyengine:jme3-blender:$jmeVersion"
    compile "org.jmonkeyengine:jme3-bullet:$jmeVersion"
    compile "org.jmonkeyengine:jme3-plugins:$jmeVersion"
    compile "org.jmonkeyengine:jme3-networking:$jmeVersion"

    compile group: "cz.advel.jbullet", name: "jbullet", version: "20101010"

    compile group: "org.cogchar", name: "ext.bundle.opengl.jmonkey", version: "1.1.3"

    compile files('libs/cai-nmgen-0.2.0.jar')

    runtime project(':assets')
}

task wrapper(type: Wrapper) {
}

task createDirs << {

    def pkg = 'spaceworld'
    def dirs = [
            file("./src/main/java/$pkg"),
            file("./src/main/resources"),
            file("./assets/Interface"),
            file("./assets/MatDefs"),
            file("./assets/Materials"),
            file("./assets/Models"),
            file("./assets/Scenes"),
            file("./assets/Shaders"),
            file("./assets/Sounds"),
            file("./assets/Textures"),
    ]

    dirs.each {
        if (!it.exists()) {
            println "Creating " + it
            it.mkdirs()
        }
        if (it.listFiles().length == 0) {
            def stub = new File(it, 'removeme.txt')
            println "Creating stub file to allow git checkin, file:$stub"
            stub.text = "Remove me when there are files here."
        }
    }
}

I don't understand how to add the dependency.

Solution

It means that the dependency com.jme3:xmlpull-xpp3:3.0.0.20140325-SNAPSHOT does not exist in the repositories you specified.

Possible reasons:

You misspelled the dependency.
You left out a repository.
Your local Maven repository or gradle cache are broken.

Consider looking at the dependency tree to figure out where this dependency comes from and what to do to resolve the issue.