Class module-info missing a super type

I'm trying to make a test case with Appium on Android with some dependencies, but one of them is causing this error:

  

Illegal class file: Class module-info is missing a super type.

The dependency that causes the problem is selenium-server-standalone-3.14 The dependencies are included as:

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation files('libs/client-combined-3.14.0.jar')
    implementation files('libs/gson-2.6.2.jar')
    implementation files('libs/java-client-6.1.0.jar')
    implementation files('libs/java-client-6.1.0-javadoc.jar')
    implementation files('libs/selenium-server-standalone-3.14.0.jar')
}

I'm using Android Studio 3.1.4.