title: Cannot generate the signed APK due to some warning
body: <p>While generating a signed APK I got these warinings</p>
  
  <pre><code>Warning: org.junit.internal.runners.statements.FailOnTimeout: can't find referenced class java.lang.management.ManagementFactory
  Warning: org.junit.internal.runners.statements.FailOnTimeout: can't find referenced class java.lang.management.ThreadMXBean
  Warning: org.junit.internal.runners.statements.FailOnTimeout: can't find referenced class java.lang.management.ThreadMXBean
  Warning: org.junit.internal.runners.statements.FailOnTimeout: can't find referenced class java.lang.management.ManagementFactory
  Warning: org.junit.internal.runners.statements.FailOnTimeout: can't find referenced class java.lang.management.ThreadMXBean
  Warning: org.junit.internal.runners.statements.FailOnTimeout: can't find referenced class java.lang.management.ThreadMXBean
  Warning: org.junit.rules.DisableOnDebug: can't find referenced class java.lang.management.ManagementFactory
  Warning: org.junit.rules.DisableOnDebug: can't find referenced class java.lang.management.RuntimeMXBean
  Warning: org.junit.rules.DisableOnDebug: can't find referenced class java.lang.management.ManagementFactory
  Warning: org.junit.rules.DisableOnDebug: can't find referenced class java.lang.management.RuntimeMXBean
  </code></pre>
  
  <p>What should I do to avoid these warnings? Thanks in advance for your help.</p>