Android Error: Apache Httpclient does not exist

Question

Now it is mandatory by google to have in the code that updating where the version of targetSdkVersionto apply the latest API’s to applications.

I changed the values of SdkVersion to 26 as recommended by google play.

    apply plugin: 'com.android.application'    
android {
    compileSdkVersion 26
    buildToolsVersion '26.0.2'

    defaultConfig {
        minSdkVersion 15
        targetSdkVersion 26
    }

But when performing the build, the application returns me the error about the package org.apache.http cannot be found together with other file properties such asclasses and variáveis.

Error:(19, 23) error: package org.apache.http does not exist
Error:(20, 23) error: package org.apache.http does not exist    
Error:(230, 13) error: cannot find symbol class HttpEntity
Error:(231, 29) error: cannot find symbol variable EntityUtils    

I’m forgetting to put some information in my code? Because the only thing I changed was the number of SdkVersion. How can I solve this problem?