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 )
  {
  }
}

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;
  }
}

Update input so we remember to check names of Actions and Computed