When using a third-party library etc., including that library, everything is in one jar file (I think).
The first one ・ IntelliJ IDEA Community Edition 2016.3.4 ・ Forge 1.7.10-10.13.4.1614 ・ Forge Gradle 1.2
Second ・ IntelliJ IDEA Community Edition 2016.3.4 ・ Forge 1.11.2-13.20.1.2386 ・ Forge Gradle 2.2-SNAPSHOT
** * Please do not write <>. Also, please keep the order of minecraft, configurations, dependencies, jar as it is. In the code below, delete between "from here" and "up to here" in the 1.11.2 environment. ** **
//from here
minecraft {
    srgExtra "PK: <The root directory of that library> <Path when making a jar file>"
}
//So far
configurations{
    shade
    compile.extendsFrom shade
}
dependencies {
    <Change compile to shade, see below for details>
}
jar {
    configurations.shade.each {dep ->
        from(project.zipTree(dep)){
            exclude 'META-INF', 'META-INF/**'
        }
    }
}
//from here
minecraft {
    srgExtra "PK: com/fasterxml/jackson/annotation com/fasterxml/jackson/annotation"
    srgExtra "PK: com/fasterxml/jackson/core com/fasterxml/jackson/core"
    srgExtra "PK: com/fasterxml/jackson/databind com/fasterxml/jackson/databind"
}
//So far
configurations{
    shade
    compile.extendsFrom shade
}
dependencies {
    shade group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.0'
}
jar {
    configurations.shade.each {dep ->
        from(project.zipTree(dep)){
            exclude 'META-INF', 'META-INF/**'
        }
    }
}