import org.realityforge.arez.annotations.Action;
import org.realityforge.arez.annotations.Computed;
import org.realityforge.arez.annotations.Container;
import org.realityforge.arez.annotations.Observable;

@Container( singleton = true )
public class SingletonModel
{
  @Observable
  public long getTime()
  {
    return 0;
  }

  @Observable
  public void setTime( final long time )
  {
  }

  @Action
  public void doStuff( final long time )
  {
  }

  @Computed
  public int someValue()
  {
    return 0;
  }
}

import org.realityforge.arez.annotations.Container;
import org.realityforge.arez.annotations.Observable;

@Container( singleton = true )
public class SingletonModel
{
  @Observable
  public long getTime()
  {
    return 0;
  }

  @Observable
  public void setTime( final long time )
  {
  }
}

--- 
+++ 
@@ -1,3 +1,5 @@
+import org.realityforge.arez.annotations.Action;
+import org.realityforge.arez.annotations.Computed;
 import org.realityforge.arez.annotations.Container;
 import org.realityforge.arez.annotations.Observable;
 
@@ -14,4 +16,15 @@
   public void setTime( final long time )
   {
   }
+
+  @Action
+  public void doStuff( final long time )
+  {
+  }
+
+  @Computed
+  public int someValue()
+  {
+    return 0;
+  }
 }
Update input so we remember to check names of Actions and Computed
