title: Where is gradle build tools version set?
body: <p>I have installed sdk build tools version 28.0.2, and set buildToolsVersion = "28.0.2" in build.gradle. Yet when I run <code>./gradlew installDebug</code>, I get an error message saying <code>The SDK Build Tools revision (23.0.1) is too low for project</code>.</p>
  
  <p>I even UNinstalled version 23.01.1 via the android studio sdk manager - but then when I run gradlew it reinstalled it!</p>
  
  <p>I ran <code>grep -ri buildtool *</code> to try and find where it might be, but the only reference I could find was in build.grade.</p>
  
  <p>I managed to work around this by upgrading my gradle version to 3.1.0. But as a result, I now get this message:
  <code>WARNING: The specified Android SDK Build Tools version (23.0.1) is ignored, as it is below the minimum supported version (27.0.3) for Android Gradle Plugin 3.1.0.</code></p>
  
  <p>Which tells me that the SDK Build Tools version <strong>is</strong> being set... somewhere!</p>
  
  <p>Where else is the required build tools version set? How do I change it so that gradle will use the latest version, rather than being stuck on an old one?</p>