Android "has already been added to output" error for jar in a project dependency

Question

I have an Android project that uses gradle with another project as dependency. Dependency project has a library jar. When I try to compile the project library is compiled twice and I get error: Error:Class no.nordicsemi.android.log.LogContract.Application has already been added to output. Please remove duplicate copies.

Here is the folder structure with files in question:

>ProjectRoot
  >dFULibrary
    >libs
      -nrf-logger-v2.0.jar
    -build.gradle
  >Logger
    -build.gradle

This is build.gradle for dFULibrary dependency:

apply plugin: 'com.android.library'

android {
    compileSdkVersion 19
    buildToolsVersion "19.1.0"

    defaultConfig {
        applicationId "no.nordicsemi.android.dfu"
        minSdkVersion 18
        targetSdkVersion 19
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

dependencies {
    compile 'com.android.support:support-v4:+'
    compile files('libs/nrf-logger-v2.0.jar')
}

This is build.gradle for Logger (main project):

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.14.4'
    }
}

apply plugin: 'com.android.application'

    android {

    compileSdkVersion 20
    buildToolsVersion '20'

    sourceSets {
        main {
            java.srcDirs "src/main/java"
            res.srcDirs "src/main/res"
            assets.srcDirs = ['assets']
        }
        androidTest.setRoot('tests')
        androidTest.java.srcDirs = ['tests/src']

    }
    dexOptions {
        preDexLibraries = false
    }
}

dependencies {
    compile 'com.android.support:support-v4:+'
    compile project':dFULibrary')
}

no.nordicsemi.android.log.LogContract.Application class is found of nrf-logger-v2.0.jar Why is it being included twice and how can I make sure it does not?

ADDITION

Here is what ../gradlew dependencies return:

_debugApk - ## Internal use, do not manually configure ##
\--- project :dFULibrary

_debugCompile - ## Internal use, do not manually configure ##
+--- project :dFULibrary
\--- com.android.support:support-v4:+ -> 21.0.2
     \--- com.android.support:support-annotations:21.0.2

_releaseApk - ## Internal use, do not manually configure ##
\--- project :dFULibrary

_releaseCompile - ## Internal use, do not manually configure ##
+--- project :dFULibrary
\--- com.android.support:support-v4:+ -> 21.0.2
     \--- com.android.support:support-annotations:21.0.2

androidJacocoAgent - The Jacoco agent to use to get coverage data.
\--- org.jacoco:org.jacoco.agent:0.7.1.201405082137 FAILED

androidJacocoAnt - The Jacoco ant tasks to use to get execute Gradle tasks.
\--- org.jacoco:org.jacoco.ant:0.7.1.201405082137 FAILED


compile - Classpath for compiling the main sources.
\--- project :dFULibrary


provided - Classpath for only compiling the main sources.
\--- com.android.support:support-v4:+ -> 21.0.2
     \--- com.android.support:support-annotations:21.0.2

I removed all the lines that had no dependencies.

EDIT #2 output from ./gradlew androidDependencies

:DFULibrary:androidDependencies
debug
\--- LOCAL: nrf-logger-v2.0.jar

debugTest
+--- LOCAL: nrf-logger-v2.0.jar
\--- debug
     \--- LOCAL: nrf-logger-v2.0.jar

release
\--- LOCAL: nrf-logger-v2.0.jar
:nRFToolbox:androidDependencies
debug
+--- LOCAL: achartengine-1.1.0.jar
\--- nrfToolbox:DFULibrary:unspecified
     \--- LOCAL: nrf-logger-v2.0.jar

debugTest
No dependencies

release
+--- LOCAL: achartengine-1.1.0.jar
\--- nrfToolbox:DFULibrary:unspecified
     \--- LOCAL: nrf-logger-v2.0.jar

BUILD SUCCESSFUL

Answer 1

Bingo, found it.

Just was interesting and I tried to find your project at Internet. And started my investigation .... :).

The problem is hidden at nrf-logger-v2.0.jar. It contains .java and .class files. Solution is to remove all .java files from it.

I did that Total Commander. Steps:

• rename nrf-logger-v2.0.jar into nrf-logger-v2.0.zip;
• go inside and remove all .java files;
• rename file back to jar;
• gradlew clean build or Build-Rebuild project at Android Studio
• voila