title: Gradle is failing to build with JCenter (using Unity + Firebase)
body: <p>So I updated Firebase to the latest version (in my Unity game), as my previous version of Firebase had an error with working on iOS devices. And now I can't build with gradle for android devices.</p>
  
  <p>Unity version: 2018.2.0f2
  Firebase version: 5.4.3</p>
  
  <p>I get this error:</p>
  
  <pre><code>FAILURE: Build failed with an exception.
  
  * What went wrong:
  A problem occurred configuring project ':Firebase'.
  &gt; Could not resolve all files for configuration ':Firebase:classpath'.
     &gt; Could not find manifest-merger.jar (com.android.tools.build:manifest-merger:26.0.1).
       Searched in the following locations:
           https://jcenter.bintray.com/com/android/tools/build/manifest-merger/26.0.1/manifest-merger-26.0.1.jar
     &gt; Could not find ddmlib.jar (com.android.tools.ddms:ddmlib:26.0.1).
       Searched in the following locations:
           https://jcenter.bintray.com/com/android/tools/ddms/ddmlib/26.0.1/ddmlib-26.0.1.jar
     &gt; Could not find dvlib.jar (com.android.tools:dvlib:26.0.1).
       Searched in the following locations:
           https://jcenter.bintray.com/com/android/tools/dvlib/26.0.1/dvlib-26.0.1.jar
     &gt; Could not find common.jar (com.android.tools:common:26.0.1).
       Searched in the following locations:
           https://jcenter.bintray.com/com/android/tools/common/26.0.1/common-26.0.1.jar
  </code></pre>
  
  <p>So, it seems that JCenter is missing some files needed by the latest version of firebase. I've read that putting <strong>google()</strong> above <strong>jcenter()</strong> in the apps .gradle file should force it to look at googles maven repo first, but it doesn't seem to help.</p>
  
  <p>My projects gradle file looks like the following:</p>
  
  <pre><code>buildscript {
      repositories {
          google()
          jcenter()
      }
  
      dependencies {
          classpath 'com.android.tools.build:gradle:3.0.1'
      }
  }
  
  allprojects {
      repositories {
          flatDir {
              dirs 'libs'
          }
      }
  }
  </code></pre>
  
  <p>I've tried changing a bunch of things, but nothing resolves this issue.
  Some help would be greatly appreciated.</p>