okhttp not found, migrating to Android developer studio (gradle)

I have an application that i have not needed to update since moving to API v2 in 2017.  Due to google enforcing a minimum targetSDK i have made modifications and the project now meets the target and is backward compatible to API 8 in eclipse.

I am trying now to migrate the eclipse project over to ADS. I have to admit that I have no prior experience until the last few days of ADS and gradle, so please be gentle!

when i build my app i am getting the following error

cannot access OkHttpClient class file for com.squareup.okhttp.OkHttpClient not found

C:\test\testproject\src\main\java\com\dropbox\core\examples\android\PicassoClient.java:19: error: cannot access OkHttpClient
                .downloader(new OkHttpDownloader(context))

i have the .jar file for okhttp in libs folder (same files that build ok with eclipse).

i have tried adding dependency so gradle downloads but it fails to find it.

implementation 'com.squareup.okhttp3:3.8.1'

and

implementation 'com.squareup.okhttp3:3.0.1'

Any help would be appreciated.

my build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    buildToolsVersion "29.0.3"
    useLibrary 'org.apache.http.legacy'

    defaultConfig {
        applicationId "com.test.testproject"
        minSdkVersion 14
        targetSdkVersion 28
        compileOptions {
            sourceCompatibility JavaVersion.VERSION_1_7
            targetCompatibility JavaVersion.VERSION_1_7
        }
    }

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles 'proguard.cfg'
        }
    }
}

dependencies {
    implementation files('libs/okio-1.13.0.jar')
    implementation files('libs/okhttp-3.8.1.jar')
    //implementation 'com.squareup.okhttp3:3.8.1'
    implementation files('libs/picasso-2.5.2.jar')
    implementation files('libs/dropbox-android-sdk.jar')
    implementation files('libs/dropbox-core-sdk-3.0.3.jar')
    implementation files('libs/httpmime-4.0.3.jar')
    implementation files('libs/jackson-core-2.7.4.jar')
    implementation files('libs/json_simple-1.1.jar')
    implementation fileTree(dir: 'C:\\android\\support\\v7\\appcompat\\libs', include: ['*.aar', '*.jar'], exclude: [])
}