Gradle에 로컬 JAR 종속성을 올바르게 포함하는 방법은 무엇입니까?

apply plugin: 'java'

sourceSets {
    main {
        java {
            srcDir 'src/model'
        }
    }
}

dependencies {
    runtime files('libs/mnist-tools.jar', 'libs/gson-2.2.4.jar')
    runtime fileTree(dir: 'libs', include: '*.jar')
}

dependencies {
    implementation files('libs/something_local.jar')
}

dependencies {
    implementation(files("libs/something_local.jar"))
}

error: package com.google.gson does not exist
import com.google.gson.Gson;