title: Plugin with id 'org.sonarqube' not found
body: <p>I am trying to implement sonar with gradle for code-coverage measure for my project. 
  we are using gradle-4.0.1 and sonarqube-6.4 .</p>
  
  <p>when I run gradle sonarqube from command line I get this error-</p>
  
  <pre><code>Plugin with id 'org.sonarqube' not found.
  </code></pre>
  
  <p>I tried few code changes but no luck, please help.
  My build.gradle file is as below- </p>
  
  <pre><code>buildscript {
      ext {
          springBootVersion = '1.5.4.RELEASE'
      }
      repositories {
          mavenCentral()
      }
      dependencies {
          classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
      }
  }
  
  apply plugin: 'org.sonarqube'
  apply plugin: "jacoco"
  apply plugin: "java"
  apply plugin: "war"
  apply plugin: "org.springframework.boot"
  
  
  sonarqube {
    properties {
      property "sonar.projectName","Spring4WebService Code Coverage Demo"
      property "sonar.projectKey", "org.sonarqubeJacocoCodeCoverage"
      property "sonar.reportPath" , "${project.buildDir}/jacoco/test.exec"
    }
  }
  
  
  test{
    ignoreFailures = true
  }
  
  
  ext {
      jacocoVersion = '0.7.6.201602180812'
  }
  
  sourceCompatibility = 1.8
  targetCompatibility = 1.8
  
  repositories {
      mavenCentral()
  }
  
  
  sourceSets {
    main.java.srcDir "src/main/java"
    test.java.srcDir "src/test/java"
  }
  
  springBoot {
    mainClass = "com.concretepage.config.WebAppInitializer"
  }
  
  dependencies {
      compile('org.springframework.boot:spring-boot-starter-web','com.fasterxml.jackson.core:jackson-databind')
      testCompile('org.springframework.boot:spring-boot-starter-test')
  }
  
  jacoco{
    toolVersion = "${jacocoVersion}"
  }
  
  jacocoTestReport {
   reports{
    html.enabled=true
    xml.enabled=true
    csv.enabled=true
   }
  }
  </code></pre>