title: Error:Cause: unable to find valid certification path to requested target
body: <p>I got the following Error in android Studio 2.2.3 when I sync gradle.</p>
  
  <p><strong>Error:Cause: unable to find valid certification path to requested target</strong></p>
  
  <p>How can I fix this issue</p>
  
  <p>I am Adding my Gradle file also</p>
  
  <pre><code>apply plugin: 'com.android.application'
  android {
  compileSdkVersion 25
  buildToolsVersion "25.0.2"
  defaultConfig {
      applicationId "com.sample.myapplication"
      minSdkVersion 16
      targetSdkVersion 22
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  } } dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
      exclude group: 'com.android.support', module: 'support-annotations'
  })
  compile 'com.android.support:appcompat-v7:23.4.0'
  compile 'com.android.support:design:23.4.0'
  compile 'com.android.support:palette-v7:23.4.0'
  testCompile 'junit:junit:4.12'
  // FireBase
  compile 'com.google.firebase:firebase-messaging:9.0.0'
  }//Add this line
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>and the project Level Gradle File</p>
  
  <pre><code>buildscript {
  repositories {
      jcenter()
  }
  dependencies {
      classpath 'com.android.tools.build:gradle:2.2.3'
      classpath 'com.google.gms:google-services:3.0.0'
  }
  }
  allprojects {
  repositories {
      mavenCentral()
      jcenter{ url "http://jcenter.bintray.com/" }
      maven { url "https://jitpack.io" }
  }
  }
  task clean(type: Delete) {
  delete rootProject.buildDir
  }
  </code></pre>