Gradle is not Compatible with library

Question

i'm developing an android application that contain .jar file which company give it to me and it usage is for background Thread.

but when i add this jar to my project libs folder i get this error

 Error:Gradle: Execution failed for task ':hc:preDexDebug'
.>com.android.ide.common.process.ProcessException:  org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.8.0\bin\java.exe'' finished with non-zero exit value 1**

i have searched this Error a lot i have seen these Q&A s:

Error: Gradle: execution failed for task ':app:preDexDebug'

Build error ,Gradle -> Error:Execution failed for task ':app:preDexDebug'. > org.gradle.process.internal.ExecException:

Error:Execution failed for task ':app:dexDebug'. com.android.ide.common.process.ProcessException

Android java.exe finished with non-zero exit value 1

why java.exe exit with value 1 in android studio

but none of them works for me .

this is my module gradle file :

buildscript {
   repositories {
    jcenter()
    }
    dependencies {
       classpath 'com.android.tools.build:gradle:1.1.1'
   }
}
apply plugin: 'com.android.application'

repositories {
    jcenter()
}

android {
    compileSdkVersion 22
    buildToolsVersion "23.0.0 rc3"

    defaultConfig {
        applicationId "androidclient.hc"
        minSdkVersion 9
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_6
        targetCompatibility JavaVersion.VERSION_1_6
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),    'proguard-rules.pro'
        }
    }

}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:22.2.1'
    compile 'com.android.support:support-v4:22.2.1'
}

NOTE:

1: when i remove the company .jar project works perfect with no error so i know cause is .jar of course

2: this jar does not build with gradle and it compiles with JDK8 (Which i used too)

3: i have tried deleting JDK and install it again and also i've checked for duplicate usage of .jar

4: i have used JDK8 & SDK 5.1 & intelliJ 14.1

this .jar is too important for project and i have to use it (No jar , no project) . well how can i solve this error ? should i tell company to compile their .jar with gradle or what ?

(if you think more info is needed for answer please tell me i will add it)